Step 1: Preheat and Prepare the Pan. Start by preheating your oven to 350°F (175°C). Line your 9x13 inch baking pan with parchment paper, allowing some overhang for easy removal later.
Step 2: Make the Crust. In a large mixing bowl, cream together 1 cup of softened unsalted butter and 1 cup of packed brown sugar using an electric mixer until light and fluffy. Gradually add in 2 cups of all-purpose flour and 1/2 tsp of salt, mixing until the dough comes together.
Step 3: Press the Crust into the Pan. Take about two-thirds of the crust mixture and press it evenly into the bottom of the prepared baking pan. Set aside the remaining mixture for later.
Step 4: Prepare the Fudge Filling. In a saucepan over medium heat, combine 1 cup of bittersweet chocolate chips and 1 can (14 oz) of sweetened condensed milk. Stir continuously until the chocolate is melted and the mixture is smooth. Remove from heat and fold in 1 1/2 cups of Andes Creme de Menthe Chocolate Mint Baking Chips.
Step 5: Assemble the Bars. Pour the fudge filling over the crust in the baking pan, spreading it evenly. Sprinkle the remaining crumb mixture over the fudge layer, followed by 1 cup of mint M&Ms on top.
Step 6: Bake the Bars. Bake the bars in the preheated oven for 25-30 minutes, or until the top is golden brown and the fudge is set. Allow the bars to cool in the pan for about 15 minutes before lifting them out using the parchment paper.
Step 7: Cool and Slice. Let the bars cool completely on a wire rack before slicing them into squares.
