Preheat the oven to 350 degrees F.
Grease a 9x13" pan with cooking spray. Set aside.
In a large mixing bowl, beat melted butter and brown sugar until well combined, about 2 minutes.
Add the eggs, one at a time, until incorporated.
Add the vanilla extract, mixing until combined.
Add the flour, baking powder, and salt, mixing with a spatula until combined.
Fold in the pretzels.
Spread the blondie dough into the prepared pan.
Drizzle the warm caramel over the dough and swirl with a knife.
Bake in the preheated oven for 30-35 minutes, until golden brown and no longer jiggly in the middle.
Cool completely.
Cut into squares. Enjoy!