Preheat the oven to 350 F. Line an 8-inch square baking dish with parchment paper {make sure the parchment paper overflows the dish}.

In a large mixing bowl, stir together the oats, flour, and brown sugar. Stir in the melted butter and peanut butter. Press the oat mixture into the prepared baking dish, reserving a 1/2 cup for later. Spoon jam across the top of the oat mixture. Sprinkle the remaining 1/2 cup of oat mixture over the jam.

Bake for 20-30 minutes, or until slightly browned and firm. Cool completely, at least 1 hour, before cutting into squares.