Grease the mug: Rub the inside of a microwave-safe mug (at least 12 ounces) with butter or oil to prevent sticking.
Whisk the base: Crack in the eggs and add heavy cream, a pinch of salt, and pepper. Whisk with a fork until smooth and slightly frothy.
Add mix-ins: Stir in cheese, chopped meat, and veggies.
If using raw mushrooms or bell peppers, pre-sauté or chop very fine to avoid extra moisture.
Microwave in bursts: Microwave on high for 30 seconds. Stir gently, scraping sides. Microwave another 20–30 seconds, then check.
Continue in 10–15 second bursts until just set in the center.
Rest and finish: Let it sit for 30–60 seconds to finish cooking from residual heat. Top with extra cheese, herbs, or hot sauce if you like.
Serve: Eat straight from the mug or loosen with a spoon and slide onto a plate.