Preheat oven to 400 degrees F (200 degrees C). (If using a countertop induction oven, preheat to 390 degrees F (199 degrees C) or use the "Combo 2" setting.) Line a baking sheet with aluminum foil; arrange bacon slices on top. Bake in the preheated oven until bacon is partially cooked through but not crispy, about 10 minutes in the conventional oven and 6 to 7 minutes in the countertop induction oven. Reduce oven temperature to 375 degrees F (190 degrees C); reduce countertop induction oven temperature to 325 degrees F (163 degrees C). Heat olive oil in a large skillet over medium heat. Add garlic; cook and stir until fragrant, about 1 minute. Add spinach; season with salt and pepper. Cook and stir until spinach turns dark green, 3 to 5 minutes. Remove from heat. Cut four 2-inch holes 3/4 of the way through each loaf, evenly spaced apart, using a small serrated knife. Remove bread cutouts with your fingers; discard or set aside for another use. Press 1 tablespoon of the spinach mixture into the bottom of each hole. Line each hole with 1 slice of bacon. Crack 1 egg into each hole; top with 1 tablespoon half-and-half. Season with salt and pepper. Sprinkle 1 tablespoon Parmesan cheese over half-and-half. Transfer loaves to a baking sheet. Bake in the preheated oven until eggs are set, about 15 minutes.