I have been using Unreal Engine for a few years now, working mostly as a UI programmer.
I find it helpful to consolidate what I learn by writing tutorials. It helps to have something to look back on when I inevitably forget something 
Blueprints
Show TMap Entries in the Same Row
ForceInlineRow or a custom inspector
Keyboard-only Blueprint Editing
Edit faster, avoid RSI, improve consistency
How to set up UI in an Unreal project
Use C++ and Blueprints to create a solid foundation for your game UI.
C++ & Blueprints UMG Workflow Video
A introductory tutorial on how to set up UIs using C++ and Blueprints.
Return Arrays of the Correct Subclass Type in Blueprints
Avoid casting with this one weird trick.
Unreal Engine UI Animation
Creating animations, events, reusable animations.
C++
Data
Show TMap Entries in the Same Row
ForceInlineRow or a custom inspector
Inheritable TMap
Make sure changes made in the parent are propagated to children.
Curve Tables
Define gameplay data using external CSV/JSON.
Unreal Engine Data Roundtable Discussion
Discussing data format issues, strengths, weaknesses
Data-driven Design in Unreal
Data Tables, Data Assets and others
Discussion
What's the deal with Verse?
No boolean? Const everything? Out-of-order evaluation?
How to Use Mastodon, as an Unreal Engine Dev
It's not much like Twitter.
Unreal Engine Data Roundtable Discussion
Discussing data format issues, strengths, weaknesses
Getting into the Games Industry
Advice on finding jobs, applying, interviewing and getting hired.
#notGDC 2022 Talks
Thanks to everyone for sharing their knowledge!
Unreal Engine Scripting Languages
What scripting languages can you use in Unreal?
Widget Reflector Video Tutorial
How to use the Widget Reflector to debug UI issues.
Useful Editor Preferences
Improve your workflow, avoid annoyances
Getting Unreal Crash Reports with BugSplat
Automatically collect crash info from your players!
Ultrawide Monitor UI Support
How to clamp your UI to an aspect ratio
In-Game Bug Reporter Best Practices
What information to inlcude, how to get the most out of it
Industries of Titan Localization
What I learned along the way.
Reimporting Assets
A single setting makes working in a team a breeze
Software & Hardware I Use
Some self-indulgence
Help and Resources for Unreal Engine
How to get help, and help yourself
Data-driven Design in Unreal
Data Tables, Data Assets and others
Things I wish I knew coming to Unreal from Unity
Gotchas and surprises I encountered
Plugins
Unreal Engine Plugins
A list of all the plugins I've worked on
BYG Localization plugin
Define Markdown-like custom syntax, use nested styles
BYG Rich Text plugin
Define Markdown-like custom syntax, use nested styles
BUIValidator Plugin
Texture settings validator plugin
Unreal Console Cheat Manager
Cheat your way to success!
A UMG C++ Tweening Library
Animate UMG widgets from C++
Text & Localization
Common UI Text Widgets
Text widgets with centralized styling, marquee and more!
Industries of Titan Localization
What I learned along the way.
BYG Localization plugin
Define Markdown-like custom syntax, use nested styles
Supporting Localized Keybindings
Setting defaults for AZERTY, QWERTZ keyboards
Localization: Advanced Plurals
More than just "one" and "other"
Pluralizing Item Names
When "strawberrys" won't cut it.
Using Curly Braces in FormatText
tldr; Wrap them in backticks
Unreal UIs and Localization
Common pitfalls to avoid as you implement user interfaces in Unreal.
UI
Using the same callback function for many UButtons
Which button was called? Now you can find out!
Common UI Button Widgets
Centralized styling, selected state, and more!
Common UI Text Widgets
Text widgets with centralized styling, marquee and more!
Common UI Introduction
What is the plugin for? What does it contain? Why should we care?
Widget Reflector Video Tutorial
How to use the Widget Reflector to debug UI issues.
UMG List View
Populate a vertical box with a huge number of elements!
Changing UI Scale in Unreal Engine
Let players make the UI larger or smaller! Or the same!
Pause Game When Window Loses Focus
Want to pause the game, reduce FPS, mute audio when the game window loses focus?
How to set up UI in an Unreal project
Use C++ and Blueprints to create a solid foundation for your game UI.
Buttons with custom hitboxes
How can I make a button with a non-rectangular hitbox?
Character Health Bar UI using C++
How to set up widgets attached to actors.
Creating Resolution-independent UIs in Unreal Engine
Design at lowest resolution, scale with DPI Scaling and Custom Application Scaling
A UMG C++ Tweening Library
Animate UMG widgets from C++
Localized Strings Using StringTable and C++
Store localizable strings in a CSV file and use them in the editor and C++.
Using the RetainerBox Widget
How to apply material effects to a group of child widgets.
Updating UserWidgets in the Editor
Using SynchronizeProperties() to show changes to Blueprint properties in the editor.
Connect C++ to UMG Blueprints with BindWidget
How to control logic from C++ and configure visuals in Blueprints.
Unreal UIs and Localization
Common pitfalls to avoid as you implement user interfaces in Unreal.
Unreal UIs and C++: Slate
After you have mastered UserWidgets and UMG, let's get down to the nitty-gritty.
Controlling UMG Animations from C++
How to call UMG animations defined in Blueprints from C++.
Unreal Engine UI Animation
Creating animations, events, reusable animations.
Unreal UIs and Texture Sizes
tldr; Multiple of 4 is great
UI Basics Series
Unreal UIs and C++: Slate
After you have mastered UserWidgets and UMG, let's get down to the nitty-gritty.
Introduction to C++ UIs in Unreal
What's the deal with Slate, UMG and Blueprints?
Creating a UserWidget in C++
How to build user widgets base classes in C++.
Creating new UWidgets in C++
Create your own custom re-usable widgets in pure C++. No Blueprints required!
Introduction to UIs in Unreal
How to start making user interfaces in Unreal using UMG, Slate and C++
Video
#notGDC 2022 Talks
Thanks to everyone for sharing their knowledge!
Intro to making UIs in Unreal Engine 5
A rambling live chat-style video about the basics of creating user interfaces in Unreal Engine 5.
Character Health Bar UI using C++
How to set up widgets attached to actors.
Uncategorized
How I Stopped Being Terrified of Slate
Talk for JetBrains GameDev Day Online 2022
New Unreal 5 Search
It's like Duck Duck Go for your game.
PlasticSCM Cheat Sheet
Notes on using PlasticSCM and Unreal
Using the Visual Logger
Unreal's Visual Logger is great for debugging spatial issues.
How to make a pull request to Unreal Engine
Be the changelist you want to see in the world.
Unreal UI Discord
Come talk about Unreal UI on Discord!
Cheat Console Cheat Scripts
Store sets of cheats in a .ini, execute them with one command.
Fuzzy Search in Unreal's Cheat Console
tldr; prefix with ? and a space.
Send HTTP POST with Unreal Engine
Attach screenshots, zips, plain form data, and send it to a server!
Testing and Test Driven Development in Unreal
It's so satisfying when all the lights turn green!
Unreal UI Best Practices
A completely subjective list of things that I do.
FRunnable and Threads
One way to set up threads in Unreal.
Fix Tick Not Being Called on Widgets
I see this one being asked quite often in the Unreal Slackers #ui chat.
Using Materials in Unreal UIs
How to apply shader effects to your UIs.
Unreal UIs and Performance
Make Unreal go fast brr