1 head of cauliflower, chopped into florets
1 teaspoon salt, divided
1 cup heavy cream
2 ounces mascarpone cheese
1 1/2 teaspoons Dijon mustard
1 1/2 cups Cheddar cheese, divided
1/4 teaspoon pepper
1/2 teaspoon garlic powder
Grease a 9" x 13" casserole dish and preheat the oven to 375 degrees Fahrenheit.
Place two inches of water into a large pot. Place a steamer basket inside and the florets inside of the basket. Sprinkle cauliflower with 1/2 teaspoon of salt.
Place the pot over high heat and steam the cauliflower for about 5 minutes, until crisp-tender. When done, transfer to a large bowl.
In a small saucepan, bring the cream to a simmer. Whisk in the mascarpone cheese and Dijon mustard until smooth.
Stir in 1 cup of the cheddar cheese into the cream mixture along with remaining 1/2 teaspoon salt, pepper, and garlic powder.
Add the cheese sauce to the steamed cauliflower in the bowl and mix well. Pour into the prepared baking dish and sprinkle top with remaining 1/2 cup of cheddar cheese.
Place in the preheated oven and bake for 15 minutes until the cheese on top has melted and the casserole is hot and bubbling throughout.