Preheat oven to 350°F. Spray four ramekins with cooking spray and set aside.
Heat olive oil in a skillet over medium heat. Saute onions and chicken for 3 minutes. Add fresh basil and saute 1 minutes. Set aside.
Arrange 2 slices of deli chicken in each ramekin covering the bottom and the sides. Crack an egg into each ramekin. Top with a couple tablespoonfuls of the chicken mixture. Top with cherry tomatoes and cheese.
Bake for 25 minutes until eggs are cooked to your preference. Serve hot.
Notes
You can use 4 slices of deli chicken if the slices are large enough to cover the muffin tin.