Preheat oven to 350°F. Grease interior of ramekins (between 4 to 6 oz in size, (see notes) with butter. Add 1 tbsp of heavy cream to the bottom of each ramekin. Crack egg on top.
Sprinkle on desired toppings (if you use something like pesto, you may want to reserve a little to spoon on top after your egg dish is finished). Fill a rectangle baking pan halfway with water and place ramekins inside (make sure your water level is not above the ramekins). Bake for about 15-30 minutes until egg is barely set (whites are just done and yolk is still soft, the timing will depend on the size of your eggs as well as how wide your ramekins are). I recommend you start checking in halfway, and then every few minutes after so you don't overcook your eggs. Let eggs cool a little (they will also continue to cook slightly) before eating. You can eat them as is, or spread onto bread or toast.
Notes
I made these in ramekins, though you are free to use other oven-safe pots, bowls, or cups that are around the same size. You want to use something between 4oz to 6oz. A 4oz ramekin will yield a thicker egg that will take a little longer to cook and the egg white might cover the egg yolk during cooking. A wider, 6oz ramekin will cook the egg faster and the egg yolk will likely stay on the surface since the egg white is more spread out.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.