Start by preheating your oven to 350°F (175°C). Grab your 9×13-inch baking pan and give it a quick coat of nonstick cooking spray to ensure your cake slides out effortlessly once it’s baked.

In a small bowl, combine the graham cracker crumbs, ¼ cup sugar, chopped nuts (if you’re using them), and ground cinnamon. Pour in the melted butter and stir until everything comes together into a coarse, crumble-like texture. Set this aside—it’s going to add that irresistible crunch to your cake!

In a large mixing bowl, whisk together the pancake mix and ¾ cup sugar until evenly blended. In a separate bowl, combine the sour cream, milk, vegetable oil, beaten egg, and vanilla extract. Stir this wet mixture until smooth, then pour it into the dry ingredients. Gently mix everything together until just combined—don’t overdo it, or your cake might lose its tender texture.

Pour the batter into your prepared baking pan, spreading it out evenly with a spatula. Now, take that delicious crumb topping you made earlier and sprinkle it generously over the top of the batter, covering every inch with cinnamony goodness.

Slide the pan into your preheated oven and let it bake for 30 to 35 minutes. You’ll know it’s ready when a toothpick inserted into the center comes out clean, with no wet batter clinging to it. Once it’s done, let the cake cool in the pan for a few minutes before cutting into it—this helps it hold its shape.

Slice your coffee cake into squares and serve it warm. The combination of the soft cake and crunchy topping is pure magic, especially with a steaming mug of coffee or tea by your side. Enjoy the moment—you’ve just baked something truly special!