Preheat oven:

Set oven to 425°F (220°C).

Whisk egg mixture:

In a large bowl, combine eggs, milk, sea salt, pepper, and paprika using a whisk until uniform. Mix in cheese; reserve.

Fry bacon and aromatics:

In a 10-inch cast iron skillet over medium heat, fry bacon, onion, and garlic until bacon starts to brown, roughly 5 minutes.

Cook vegetables:

Add vegetables, cover, and cook until tender and bacon is fully browned, stirring from time to time, about 5 minutes.

Pour in eggs:

Lower heat to medium, pour in egg mixture, and stir rapidly into the bacon and vegetables until well dispersed.

Cook on stovetop:

Cook over medium heat for 4-5 minutes until the edges are firm.

Bake frittata:

Move skillet to the preheated oven and bake for 7-10 minutes until the top is golden brown and set. (The frittata will rise in the oven; it falls as it cools.)

Cool and serve:

Take out of the oven, allow to cool for 10 minutes, then slice and serve.