Remove any discolored or loose outer leaves from the brussels sprouts.
Cut the tough part of the stem off the brussels sprouts with a paring knife, but avoid cutting the leaves to prevent them from falling off during cooking
Bring a saucepan of water to a boil;
reduce heat to medium-low
Cook the sprouts for 10 minutes. Drain, and set aside.
Melt the butter in a saucepan over medium heat and stir in the flour, salt, and pepper. Cook the mixture until it turns a slight tan color, about 1 minute; whisk in the milk. Bring to a simmer, whisking constantly, and cook until thickened, about 2 minutes. Stir in velveeta cheese until the cheese has melted and the sauce is thick and smooth. Transfer the Brussels sprouts into the sauce, stirring to coat