Homemade Pierogi with Caramelized Cabbage and Onions - Simple Seasonal

Ingredients

• 2 C all-purpose flour
• 1/2 tsp salt
• 1 large egg
• 1/2 C sour cream
• 4 Tbsp butter at room temperature
• 1 lb russet potatoes or 1-1 1/2 C leftover mashed potatoes
• 2 Tbsp butter
• 1 1/2 C grated sharp cheddar cheese
• 1/4 tsp onion powder
• 1 tsp plus 1/4 tsp salt
• 1/8 tsp black pepper
• 4 Tbsp butter
• 2 C chopped sweet yellow onion
• 4 C chopped cabbage
• salt and pepper to taste
• 1 C sour cream for serving