Cook bacon in a large cast-iron skillet over medium until crispy, 10 to 12 minutes, turning often. Transfer to a plate lined with paper towels, reserving drippings in skillet.
Add potatoes, onion, and bell pepper to reserved drippings in skillet, and spread in an even layer. Cover and cook over medium until potatoes soften, about 5 minutes. Uncover and cook, without stirring, until potatoes are just browned and beginning to crisp, about 5 minutes. Stir in garlic, salt, and pepper. Cook, without stirring, in 6 (2-minute) intervals, stirring in between each 2-minute interval, until potatoes are browned and crisp.
Crumble bacon; add bacon and spinach to skillet. Remove skillet from heat, and stir until spinach wilts, about 2 minutes. Serve with hot sauce.