Preheat the oven to 350F and line a 9x9 square pan with parchment paper (or give it a quick spray with non-stick spray).
In a small bowl, measure out the graham cracker crumbs. Then, melt the butter and add the melted butter to the crumbs and mix until fully combined.
Press the graham crumbs firmly into the bottom of your square pan. This will be a fairly thin layer.Cook's Note: I like to put a small plastic sandwich bag or plastic wrap on my hand to use to press down on the graham crumb crust in the pan.
Sprinkle the pretzel pieces and both chocolate chips over the graham cracker layer.
Mix the vanilla extract into the condensed milk. Then, pour the condensed milk over the chocolate & pretzels, trying to keep away from the edges of the pan.
Bake at 350F for 22-25 minutes, until the the top is bubbling and golden. Let cool and then cut into bars the size of your choosing.