Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until starting to brown, about 5 minutes. Drain bacon slices on paper towels.
Line 6 cups of a nonstick muffin tin with bacon slices. Chop leftover bacon slices and sprinkle over the bottom of each cup.
Whisk eggs, milk, butter, parsley, salt, and pepper together in a large bowl. Stir in ham and mozzarella cheese.
Pour egg mixture into the bacon-lined cups; top with Gouda cheese.
Bake in the preheated oven until Gouda cheese is melted and eggs are set, about 15 minutes.
