Preheat your oven to 350°F (175°C). Spray your preferred baking dish—either a square or a 9x13-inch rectangle—with cooking oil and line it with parchment paper to prevent sticking. Set the dish aside while you prepare the batter.

In a large bowl, combine the pumpkin puree, heavy cream, nut-based milk, eggs, sugar-free sweetener, and pumpkin pie spice. Mix until the ingredients are well incorporated and the mixture is smooth. Pour the pumpkin mixture into the prepared baking dish, spreading it evenly.

Evenly sprinkle the keto cake mix over the pumpkin base in the dish. Next, drizzle the melted unsalted butter evenly over the cake mix layer. Finish by scattering the chopped pecans on top for a delicious crunch. I like to press the pecans in slightly with the back of a spoon so they bake into the top layer.

Bake at 350°F for 40-50 minutes if using a 9x13-inch baking dish, or 50-60 minutes if using a square dish. The cake is done when the top is spongy to the touch and not jiggly when the dish is gently shaken. Remove from the oven and let it cool for a few minutes before serving. For an extra treat, I like to serve this warm with a dollop of whipped cream or a scoop of low-carb ice cream.