Preheat oven to 350 F (180°C). Spray a 9 x 9 x 2 inch (23 x 23 x 5 cm) baking pan with cooking spray and set aside. Combine flour, baking powder, cinnamon and salt in a medium bowl. Stir in dried fruit, oatmeal and peanuts and set aside.
Beat together eggs, brown sugar, peanut butter and vanilla in a large bowl until smooth. Stir in flour mixture. Pour into prepared pan. Bake in oven until cake tester or toothpick inserted in centre comes out clean, about 20 to 25 minutes. Cut into and cool on wire rack.