Heat a medium skillet over medium heat and cook bacon until crispy. While the bacon cooks, season chicken on both sides with salt and pepper. Transfer bacon to a paper towel–lined plate to drain and increase heat to medium-high. 4 slices bacon, 4 boneless skinless chicken breasts, ½ teaspoon salt, ¼ teaspoon black pepper
Sear chicken for about 5 minutes per side, or until golden brown. Transfer to the plate with bacon.
Add a splash of water to the pan and scrape up any browned bits. Add spinach and cook, stirring occasionally, until wilted. 142 g baby spinach (8 to 10 cups loosely packed)
Spread spinach in a casserole dish large enough to hold all 4 chicken breasts. Arrange chicken in a single layer over spinach, then top each with a slice of bacon, tomato slices, and cheese. 3 to 4 Roma tomatoes cut into 12 to 16 slices, 3 to 4 Roma tomatoes cut into 12 to 16 slices, 1 cup grated cheddar cheese (115 g)
Bake for 20 minutes, or until the internal temperature reaches 165°F (74°C). Remove from oven and let rest for 5 minutes before serving.
Notes
Store leftovers covered, in the fridge, for up to 3 days.