Get your oven and baking dish ready! Preheat the oven to 350 degrees Fahrenheit, and line a 9 x 9-inch pan with parchment paper.

Turn your graham crackers into graham cracker crumbs using your desired method, then add the brown sugar and melted butter. Stir until well combined.

Press the buttery graham cracker crust into the bottom of the pan, making sure to fill the corners well.

Bake the crust for 8 minutes, then remove and set aside to cool completely.

While the crust is baking, use an electric mixer to cream together the softened cream cheese and white sugar. Beat them until they're light and fluffy! Then slowly add both eggs and the egg yolk, one at a time.

Use the hand mixer to mix in the sour cream, lemon juice, and vanilla extract. Here's the first layer of your cheesecake!

Pour two cups of this initial cheesecake filling on to the top of your prepared pan with the graham cracker crust. Use an offset spatula to spread it evenly, then pop the pan in the freezer to quickly set in preparation for the next layer.

Add the pure pumpkin puree and all of those fall spices to the remaining cheesecake mixture and mix until well combined.

Pour the pumpkin layer of cheesecake filling on top of the set plain cheesecake filling, spreading it evenly.

Bake the two layers of cheesecake for 30 minutes, at the same oven temperature as the crust.

Meanwhile, use a food processor or blender to combine the pecans, vanilla, flour, white sugar, brown sugar, spices, and butter until a soft crumble topping forms.

After the cheesecake is finished baking, coat it with the pecan crumble and then place it back in the oven for another 45 minutes.

When these 45 minutes are up, the cheesecake should have firm edges, but a jiggly center. Turn the oven off, open the oven door a crack, and let the residual warmth in the oven continue to bake the cheesecake bars for another hour.

Remove the cheesecake from the oven, cover it tightly with aluminum foil or plastic wrap, and place it in the fridge for at least 6 hours prior to serving.

For a clean cut when serving, slice with a large knife dipped in hot water. Serve with ice cream or whipped cream!