You've had potatoes au gratin, but how about beets au gratin? Baked into a cheesy casserole with a creamy garlic sauce, this recipe will surprise and delight your guests. Gorgonzola's robust and salty flavor compliments the sweetness of the beets that comes out during the baking process.
1. Preheat oven to 375°F. Lightly grease a 13-by-9-inch baking dish.
2. Melt butter in a medium stockpot over medium heat. Add garlic and rosemary and cook 30 seconds, until fragrant. Add flour and cook, stirring, 1 minute, until golden.
3. Raise heat to high and slowly pour in milk, stirring to break down clumps. Bring to a boil, lower to a simmer, and cook until thickened, 2 to 3 minutes, stirring. Stir in cheese, salt, and pepper; whisk to combine, and remove from heat.
4. Arrange one-third of the beets and onions on the bottom of the prepared pan. Pour one-third of the cheese mixture evenly over. Repeat until vegetables and cheese mixture are all used. Top with cheese and bake, covered, 45 minutes. Uncover and continue baking another 20 minutes, until bubbling. Remove from oven and cool 15 minutes before serving.