Line the slow cooker with two strips of nonstick foil or parchment paper, crossing them to form a plus sign. Leave enough overhang to lift the cake out after cooking.

Spray the lining with cooking spray.

In a large bowl, whisk together the flour, baking powder, baking soda, pumpkin pie spice, and salt.

In a separate bowl, beat the softened butter and sugar until fluffy.

Add the eggs and beat until combined.

Add the pumpkin puree and beat until combined.

Gradually add the flour mixture, mixing until incorporated.

Spread the batter evenly in the prepared slow cooker.

Cover and cook on HIGH for 2½–3 hours, or until a toothpick inserted into the center comes out clean.

Turn off the slow cooker and let the cake cool for about 30 minutes.

Use the lining to lift the cake out. Slice and serve with your choice of toppings.