Preheat oven to 350 degrees. Spray the bottom and sides of a 11x7 pan with non-stick cooking spray. Cut a piece of parchment paper that will fit the bottom of the pan and overlap two sides of the pan so you can pull the bar out later on.
In a large mixing bowl, add in the butter and peanut butter and mix with a hand mixer until incorporated.
Add in the brown sugar and granulated sugar and mix until light and fluffy.
Add in the egg and vanilla and mix until combined. Scrape down the sides.
Add in 2 and ½ cups of all purpose flour, baking soda and salt. Mix on low until the flour is almost completely incorporated and then turn mixer up to high and beat for an additional 30 seconds.
Set 1 cup of dough aside in a small bowl.
Press the remaining peanut butter cookie dough into the prepared pan. Make sure it's evenly distributed.
Add the 1 cup of strawberry jam or jam flavor of your choice. Spread the jam evenly onto the cookie dough.
Add the remaining ¼ cup of flour to the 1 cup of peanut butter cookie dough that was set aside. Mix with a spoon or spatula until all of the flour is incorporated.
Crumble the cookie dough onto the top of the bars. Try not to push the crumbled down into the jam.
Place into the oven and bake for 27 minutes until the crumble is golden brown. Remove from the oven and let cool.
Place into the fridge overnight to set up.
Pull the bars out of the pan using the parchment paper handles. Cut and serve.
Notes
To store any leftover bars, place in an airtight container at room temperature for 2-3 days or up to a week in the refrigerator.