Preheat your oven, line your 9x9 inch pan with parchment paper and spray with non-stick spray.
Prepare your brownie mix according to the directions on the package.
Melt the 4 TBSP of butter and pour over the bottom of the pan. Evenly sprinkle on your 1 cup of combined snack mix. You can break up pretzels and chop your nuts, but you should only use a total of 1 cup.
Pour your brownie batter over your butter and snack mix. Bake according to the package. Make sure you are using the time and temperature for 9x9 inch pan.
When your cake tester comes out clean, remove the brownies from the oven and let cool down before cutting.