Pre-heat your oven to 350 degrees. Spray an 8”x8” baking pan with cooking spray and line it with parchment paper. You want to make doubly sure this cake doesn’t stick.
Place the bananas in a large mixing bowl and mash with a fork until very smooth. Warm the peanut butter in the microwave for 20-25 seconds until soft and pourable, and add it to the bowl along with the coconut oil, honey, and eggs. Whisk until everything is well combined.
In a separate bowl, combine the oats, flour, salt, cinnamon and baking powder.
Add the dry ingredients to the wet ingredients and stir until well incorporated.
Pour the batter into the prepared baking dish and smooth the surface with a spatula. Drop small spoonfuls of jam on top, then use a butter knife to swirl it into the batter. (Try not to over-swirl, or you’ll lose that pretty marbled effect.)
Bake for 30-35 minutes until the top is set and a tester (i.e. the tip of a sharp knife or a wooden skewer) comes out clean. Let your cake cool for at least 15 minutes before slicing.