Bacon Alfredo Sauce: Cook bacon in an oven-proof skillet over medium heat until well browned and crispy, about 10 minutes. Remove to paper towel-lined plate and reserve. Leave residual bacon fat in skillet.
To bacon fat, add butter and heat until just melted. Add garlic and cook an additional 2 minutes. Add flour to skillet, stir to combine, and cook for 2 more minutes.
Whisk in heavy cream and bring to slight simmer. Add in greens of choice (spinach or kale) and cook until just wilted. Stir in half of Parmesan cheese.
Gently crack eggs into bacon Alfredo sauce and sprinkle with remaining Parmesan cheese.
Bake until whites are just set, about 10 minutes. Season to taste and garnish with reserved cooked bacon. Serve with toasted bread.