Preheat oven to 350ºF and line 8 muffin tins with paper liners. Whisk together eggs, basil, sea salt and black pepper in a medium mixing bowl until thoroughly combined. Stir in bacon, mushrooms, and feta cheese.
Scoop mixture evenly into muffin tins and bake for 30-35 minutes or until the center of egg cups is set. Cool at room temperature for 10 minutes before enjoying. Serve alongside fresh berries