Meanwhile, in a 12-inch skillet over medium-high heat, melt butter. Cook eggs until just scrambled, stirring constantly. Remove to a bowl.
In the same skillet, heat peanut oil. Over medium heat, cook garlic until lightly browned. With a slotted spoon, remove garlic to bowl with eggs.
In drippings remaining in skillet over medium-high heat, cook chicken until well-browned and cooked through, stirring constantly. Add salt and crushed red pepper.
Stir in egg mixture, peanut sauce, bean sprouts, and cooked pierogies. Toss to mix well. Garnish with chopped peanuts and scallions. Serve Pierogies Pad Thai and enjoy!