Preheat oven to 375°F. Brush bacon with brown sugar, maple syrup, and cayenne mixture. Bake 18-22 minutes until caramelized.
Mix all burger sauce ingredients, refrigerate 30 minutes for flavors to meld.
Cook onion discs in butter and oil over medium heat 15-20 minutes until caramelized. Deglaze with balsamic vinegar.
Season ground beef with salt, pepper, and garlic powder. Form into 12 patties with thumb indents.
Cook patties 3 minutes per side, top with cheese slices during final minute.
Toast slider buns until golden brown and slightly crispy.
Assemble: spread sauce on buns, add patty, candied bacon, and onion disc.
Serve immediately or warm assembled sliders in 350°F oven for 8-10 minutes.
Notes
- Candied bacon can be made 2 days ahead and stored covered
- Keep onion discs intact for best presentation
- Make sauce ahead for better flavor development
- For parties, use pull-apart presentation method