Preheat oven to 350°F. Grease a 13x9-inch baking pan.

In a small bowl, combine 1 1/2 cups graham cracker crumbs, 3/4 cup packed brown sugar, 3/4 cup chopped walnuts or pecans, and 1-1/2 teaspoons ground cinnamon. Stir in 2/3 cup melted butter until the mixture is evenly moistened and crumbly. Set aside.

Prepare 1 package yellow cake mix (regular size) according to the package directions.

Pour about half of the prepared cake batter into the greased 13x9-inch pan and spread it into an even layer.

Evenly sprinkle half of the graham cracker mixture over the batter.

Carefully spoon the remaining batter over the streusel layer in dollops; gently spread or smooth to cover as much of the streusel as possible without mixing the layers.

Sprinkle the remaining graham cracker mixture evenly over the top.

Bake at 350°F for 30–40 minutes, or until a toothpick inserted in the center comes out clean.

While the cake cools slightly, make the glaze: in a small bowl, combine 1/2 cup confectioners' sugar and 1 tablespoon milk; whisk until smooth.

When the cake is warm (not piping hot), drizzle the glaze over the top. Allow the cake to cool until the glaze sets before slicing and serving.