Prep & Par-Bake the Puff Pastry: Preheat oven to 350°F (175°C). Lightly grease a mini muffin pan.
Cut the puff pastry into 2-inch squares and gently press one square into each cup, forming small shells.
Dock the bottoms with a fork and bake for 5–10 minutes, just until slightly puffed and lightly set.
Remove from oven and use the back of a spoon to press the centers down to make room for filling.
Make the Spinach Artichoke Layer: In a medium bowl, stir together the spinach, artichokes, cream cheese, mayo, Gruyère, garlic powder, onion powder, and a pinch of salt and pepper until smooth and creamy.
Make the Quiche Mixture: In a separate bowl, whisk together the eggs, half-and-half, salt, and pepper. Stir in the Gruyère cheese.
Assemble the Bites: Spoon about 1 teaspoon of the spinach artichoke mixture into the bottom of each pastry cup.
Then pour the egg mixture over top, filling each cup about three-quarters full.
Bake: Return the pan to the oven and bake for 21–25 minutes, or until the centers are just set and the tops are golden.
Serve: Let cool a few minutes before removing from the pan. Serve warm or at room temperature — they’re delicious either way!