Preheat the oven to 350°F.

Grease an 8×8 square cake pan with butter and line it with parchment, leaving an overhang of parchment on a couple sides to help lift the cake out later.

Mix the dry ingredients in a bowl (flour, baking soda, baking powder, salt, cinnamon) and set aside.

Add the melted butter and brown sugar to another large bowl and mix for about a minute using a whisk or handheld electric beater. Mix in the yogurt and peanut butter, then the mashed bananas, eggs, and vanilla and mix thoroughly.

Add the dry ingredients and mix them with the wet until combined. Be careful not to overmix or the cake will become gummy.

Pour half of the cake batter into the prepared square pan. Spread the jam into a layer on top of the cake batter, then top the jam with the rest of the cake batter and even it out. *Tip: if your jam is too thick to spread, you can warm it slightly in a pot or microwave to thin it out.*

Mix flour, brown sugar, salt, cinnamon, and chopped peanuts together. Mix in the melted butter and the peanut butter. The texture should be crumbly and not too dry or too wet, and it should stick together when you squeeze it in your hands, kind of like stiff cookie dough. Sprinkle the crumble over the top of the cake until it’s in an even layer.

Bake the cake for 60 minutes or until the internal temperature reaches 200°F. If the crumble is getting too dark, cover the cake with nonstick foil.

Cut into squares and enjoy.