Preheat the oven to 350°F and spray an 8x8-inch baking pan with nonstick spray.
Cook the elbow macaroni according to package directions until al dente, drain, and transfer to a large bowl.
Warm the 2 cups milk in a small saucepan over medium heat until hot but not boiling; remove from heat and set aside.
Melt the 1/4 cup butter in a medium saucepan over low heat. Whisk in the 1/4 cup flour and cook, stirring constantly, about 3 minutes until smooth and bubbly.
Gradually whisk the warm milk into the roux, then increase heat to medium-high and bring the sauce just to a boil, stirring frequently; reduce heat to low and simmer a few minutes, stirring occasionally.
Stir in 1/2 teaspoon salt, 1/2 teaspoon Tabasco, and freshly ground black pepper to taste. Add the 1/2 cup heavy cream and simmer 3–4 minutes, stirring occasionally.
Stir 12 ounces of the shredded cheddar into the sauce until melted and smooth.
Pour the cheese sauce over the drained pasta and stir to coat evenly. Transfer the mixture to the prepared baking pan and sprinkle the remaining 4 ounces of shredded cheddar on top.
Bake for 20–30 minutes until bubbly. If desired, broil 2–3 minutes to brown the top, watching carefully to avoid burning.