- 4 teaspoons butter, softened
- 2 large onion, shredded
- 2 cups baby carrots, shredded
- 1/2 cup butter, melted
- 1/2 cup grated Parmesan cheese
- 2 teaspoons garlic powder, or more to taste (optional)
- 3 eggs
- 4 egg yolks
- 1/2 cup white sugar
- 1 1/2 cups all-purpose flour, or as needed
- 1 cup shredded mozzarella cheese
- Grease bottoms and sides of each ramekin with 1 teaspoon butter.
- Combine shredded onion and carrots in a large bowl. Add 1/2 cup melted butter; mix thoroughly. Stir in Parmesan cheese and garlic powder; mix well to combine.
- Combine eggs, egg yolks, and sugar in another large bowl; beat with an electric mixer until smooth. Gradually blend in enough flour to make a smooth batter. Beat in onion mixture on low speed until thoroughly incorporated. Fold in mozzarella cheese.
- Divide batter among ramekins, filling them almost to the top. Refrigerate until firm, 1 to 3 hours.
- Preheat oven to 350 degrees F (175 degrees C).
- Bake in the preheated oven until souffle batter puffs up above the edge of the ramekins, about 30 minutes.