- 3 tablespoons unsalted butter, plus more for dish
- 1/2 cup gluten-free crisp puffed-rice cereal, slightly crushed
- 1 ounce parmesan, grated (1/4 cup)
- 1 small yellow onion, diced small
- 2 tablespoons potato starch
- 2 cups whole milk, warmed
- 3/4 pound cheddar, shredded (3 cups)
- 1 teaspoon dijon mustard
- 3/4 pound gluten-free penne, cooked until al dente and drained
- Unsalted butter
- Coarse salt and ground pepper
- 1. Preheat oven to 350 degrees. Butter six 8-ounce ramekins or a 2-quart baking dish. Microwave 1 tablespoon butter until melted, then toss with cereal and Parmesan.
- 2. In a medium saucepan, melt 2 tablespoons butter over medium. Add onion and cook until softened, 4 minutes. Sprinkle with potato starch and cook 1 minute. Slowly whisk in milk and cook, whisking constantly, until thickened, about 3 minutes. Remove from heat and stir in cheddar and mustard until smooth; season with salt and pepper. Add pasta and stir to coat; transfer to ramekins or baking dish. Sprinkle with cereal mixture and bake until sauce is bubbling and topping is golden, 15 to 20 minutes.