Heat butter in a large skillet over medium heat. Saute onion until soft. Add sausage, and cook until evenly brown. Drain, crumble, and set aside.
In a medium bowl, whisk together eggs, Ranch dressing and milk. Stir in shredded cheese. Season with hot sauce, salt, pepper and sugar.
Spread sausage mixture in the bottom of crust. Cover with egg mixture, and shake lightly to remove air, and to level contents.
Bake in preheated oven for 15 to 20 minutes. Reduce heat to 350 degrees F (175 degrees C), and bake 45 to 50 minutes, or until filling is puffed and golden brown. Remove from oven, prick top with a knife, and let cool 10 minutes before serving.