• Preheat the oven to 350°F (180°C). Grease a 6-inch round springform pan (15 cm) with olive oil. Set aside.
• In a large bowl, beat egg, pumpkin puree, natural peanut butter, and olive oil until smooth.
• Fold in flour, oats, and baking soda if used.
• Stir to combine and form a thick, smooth cake batter.
• Pour the batter into the prepared pan and bake for 25-30 minutes in the center rack of the oven until a toothpick inserted in the center comes out clean.
• Cool down on a wire rack before frosting.

Pumpkin frosting

• Cut the cooled cake in half to form two cake layers.
• Stir the pumpkin puree and plain Greek yogurt - it will be very liquid but add moisture to the cake. Spread between the cake layers.
• Decorate with drops of pumpkin puree or grated carrots.

Storage

• Store leftover in the fridge, wrap in foil and keep up to 4 days.