Lemon Poppy Seed Dump Cake

Lightly coat a 3 1/2- or 4-quart slow cooker with cooking spray; set aside. In a large bowl whisk together the buttermilk, egg, butter, and vanilla until combined. Stir in the remaining ingredients until smooth.

Spoon batter into the prepared cooker. Cover and cook on low for 2 1/4 to 2 3/4 hours or until internal temperature of cake is between 190°F and 200°F and center appears nearly set, rotating crockery liner once during cooking. Remove crockery liner from cooker. Let cool on a wire rack 10 minutes. Loosen sides of cake and remove from cooker. Cool completely.