Copycat Starbucks Pumpkin Cream Cheese Muffins

Name: Copycat Starbucks Pumpkin Cream Cheese Muffins
Ingredients: 1 large egg; 1/2 (15-oz.) can pumpkin puree (about 7 Tbsp.); 1/2 c. sour cream; 1/4 c. (53 g.) packed light brown sugar; 1/4 c. (50 g.) granulated sugar; 1/4 c. neutral oil; 1 1/2 tsp. pure vanilla extract; 1 c. (120 g.) all-purpose flour; 1 tbsp. pumpkin pie spice; 1 tsp. baking powder; 1/2 tsp. baking soda; 1/2 tsp. ground nutmeg; 1/2 tsp. kosher salt; 1/4 tsp. ground ginger; 1 (8-oz.) pkg. cream cheese, softened; 1 tsp. pure vanilla extract; 1/4 c. coarsely chopped raw pepitas; Demerara sugar, for sprinkling