Preheat the oven to 350F, and generously spray a 9x5 loaf pan with nonstick spray.

In a large bowl, use a mixer to beat together the butter and sugar until light and fluffy.

Add in the egg and vanilla, and beat to combine; then add in the mashed bananas.

Pour in 1 cup of the flour, along with the salt, baking powder, and baking soda.

Mix until combined, then add in the milk and mix in slowly.

Finally, add in the rest of the flour and mix until smooth.

Add about half the peanut butter into the batter, and mix vigorously to combine.

Pour the batter into the prepared pan, and drop spoonfuls of the remaining peanut butter and jam on top.

Using a butter knife, swirl the toppings around and into the banana bread. Make sure you don't mix them in too much!

Bake for about 40 minutes in preheated oven, then cover with foil and bake for 20-30 additional minutes.

Let cool completely before removing from pan and cutting!