Step 1

Preheat oven to 350°F. Line an 8 x 8-inch square baking dish with aluminum foil and lightly spray with non-stick cooking spray. Set aside.

Step 2

In a large bowl, whisk together 1-1/2 cups pretzel pieces, flour, baking powder and salt.

Step 3

Melt the butter in a saucepan over medium heat. Remove from the heat and stir in the brown sugar. Let cool slightly, then whisk in the eggs and vanilla. Stir butter mixture into the pretzel crumb mixture. Fold in 1/2 cup each peanut butter chips and semisweet chocolate chips.

Step 4

Spread the batter in the prepared dish. Scatter the remaining 1/2 cup pretzel pieces, 1/4 cup peanut butter chips and 1/4 cup semisweet chocolate chips on top of the batter.

Step 5

Bake until golden and a toothpick inserted into the center comes out clean with a few crumbs, 40-45 minutes. Let cool completely in the pan on a rack, then lift the foil to remove the bars and cut into squares.