1Preheat an oven to 350 degrees F (175 degrees C). Grease a 8x8 inch baking dish.
2Melt the butter in a saucepan over medium-low heat. Whisk in the flour, and stir until the mixture becomes paste-like and light golden brown, about 5 minutes. Gradually whisk the milk into the flour mixture, and bring to a simmer over medium heat. Cook and stir until the mixture is thick and smooth, 10 to 15 minutes. Remove from the heat, and whisk in the Cheddar cheese until melted. Season with salt and pepper.
3Line the prepared baking dish with half of the asparagus spears. Pour in half of the cheese sauce, top with the remaining asparagus spears, then pour on the remaining sauce. Sprinkle with the slivered almonds.
4Bake in the preheated oven until the asparagus is hot and the sauce is golden brown on top, about 20 minutes.
Footnotes
Tip
Aluminum foil helps keep food moist, ensures it cooks evenly, keeps leftovers fresh, and makes clean-up easy.