Preheat your oven to 180°C (350°F) so it’s fully heated before baking, and lightly grease each cavity of a muffin tray with a small amount of oil or butter to prevent sticking and make removal easier later.
In a large mixing bowl, add the Greek yogurt, eggs, garlic powder, paprika, salt, and black pepper. Whisk or stir the mixture thoroughly until it becomes smooth, creamy, and evenly combined with no streaks of egg remaining.
Add the cooked, shredded chicken and finely chopped spinach into the bowl. Make sure the spinach is dry (if cooked, squeeze out excess moisture) to avoid watery cups.
Using a spatula or spoon, gently fold the chicken and spinach into the yogurt mixture until everything is evenly distributed. Mix carefully and avoid overmixing so the texture stays light rather than dense.
Add the shredded cheese to the mixture and stir lightly just until incorporated, allowing small pockets of cheese to remain for a better texture and flavor.
Spoon the mixture evenly into the prepared muffin cups, filling each about 3/4 full. This gives enough space for the mixture to rise slightly without overflowing.
Place the muffin tray in the preheated oven and bake for 20–25 minutes. The tops should look set, slightly firm to the touch, and lightly golden in color when done.
Remove the tray from the oven and let the cups rest for 5–10 minutes. This helps them firm up and makes them easier to remove without breaking.
Carefully take the cups out of the tray using a spoon or by gently loosening the edges, then place them on a plate or rack.
Serve warm for the best texture and flavor, or allow them to cool completely and store in an airtight container for later use.