This recipe is from Saveur I love the combination of the shortbread base, sweet caramel and salty pretzels. It takes me at least 30+ minutes to get the caramel topping up to 240 degrees.
FOR THE SHORTBREAD:
1¼ cup all-purpose flour
¼ tsp. salt
½ cup (1 stick) unsalted butter, softened
⅓ cup brown sugar
1 tsp. vanilla extract
FOR THE CARAMEL TOPPING:
¾ cup (1½ sticks) unsalted butter
1¼ cups light brown sugar
¼ cup honey
¼ cup maple syrup
½ tsp. salt
1 cup heavy cream
6 cups (about 9 oz.) small pretzel twists, lightly broken up
1. Make the shortbread: Position a rack in the center of the oven and preheat to 350°. Line a 9″ x 13″ baking pan with parchment paper, folding paper up and over the sides of the pan. In a small bowl, whisk together flour and salt, and set aside. In the bowl of an electric mixer fitted with the paddle attachment, beat together the butter and brown sugar at medium speed until combined, about 1 minute. Beat in the vanilla, change speed to low, and add the flour-salt mixture. Mix until crumbly, 10-15 seconds. Pat the dough evenly into the bottom of the parchment-lined pan, and prick dough all over with a fork. Bake 15-18 minutes, until just golden brown around the edges. Remove from oven and allow to cool slightly.
2. Make the caramel: In a large saucepan over medium heat, combine the butter, brown sugar, honey, maple syrup, and salt. Stir regularly until mixture is foamy and slightly thickened, about 10 minutes. Add cream and cook, stirring occasionally, until a candy thermometer inserted into the caramel registers 240°F (soft ball stage), about 11 minutes. Add the crushed pretzels and quickly incorporate into the caramel.
3. Pour the pretzel-caramel mixture over the baked shortbread, spreading the mixture evenly. Return to the oven until the topping is bubbling, 12-15 minutes. Remove from the oven and allow to cool completely. Remove from the baking pan by lifting the edges of the parchment paper; unfold the paper and slice into bars. Serve immediately, or bars will keep for up to 1 week in an airtight container.