Preheat oven to 350 degrees.
Line a 9 x 13 baking pan with parchment paper.
In a stand mixer, or use a hand mixer and medium bowl, mix the softened butter and brown sugar.
Add the gluten free flour and mix until crumbly.
Put crust into pan and use hand to lightly pat crust mixture onto the bottom of the baking pan.
Bake for 15-17 minutes.
Remove from oven.
In a small saucepan add the butter, maple syrup, corn syrup, brown sugar and vanilla and heat on medium-high heat.
Stir and let mixture heat to boiling.
Once boiling let cook for 2 minutes, stirring frequently.
Sprinkle the nuts and the pretzels over the crust.
Pour the hot liquid over the top of the bars.
Place baking pan back in the oven and bake for another 15 minutes.
Remove and let cool completely before cutting.
Enjoy!