Step 1

Preheat the oven to 350°F. Generously grease the inside of a 10-cup Bundt pan and sprinkle with flour. Set aside.

Step 2

Using an electric mixer (a handheld or stand mixer will do), mix the butter on medium speed until smooth, about 2 minutes. Add the brown and granulated sugars. Mix for another 2 minutes. Stop the mixer and scrape down the sides of the bowl.

Step 3

Add the eggs and vanilla extract then mix on medium speed until creamy and combined. Add the baking soda, baking powder, cinnamon, salt, and nutmeg. Blend on low speed to combine.

Step 4

Sprinkle in about half of the flour and mix to combine. Add the buttermilk and mix until it’s absorbed into the batter. Add the remaining flour and mix by hand with a rubber spatula until mostly combined. Add the pumpkin and fold together until the batter is smooth and uniform.

Step 5

Scrape the batter into the prepared pan and smooth out with a spatula. Bake for 28 to 32 minutes, or until a toothpick inserted in the center of the cake comes out clean or with a few moist crumbs. Remove from the oven and set a timer for 20 minutes.

Step 6

During the last 10 to 15 minutes of baking, make the toffee sauce. Place the heavy cream, brown sugar, and butter in a saucepan over medium heat. Stir until the butter melts and the mixture simmers. Continue cooking, stirring every so often, for 8 to 10 minutes or until the toffee sauce thickens. It will bubble then reduce and darken in color. Turn off the heat and cover to keep warm.

Step 7

Immediately after the cake comes out of the oven, poke holes all over the cake. Pour about ⅓ of the toffee sauce on top. Let soak until the 20 minute timer goes off.

Step 8

At this point, flip the cake out of the pan. Set a large plate or cutting board on top of the cake. Holding the pan and plate together, swiftly flip everything over and remove the pan. Poke the top of the cake and drizzle on another ⅓ of the toffee sauce. Serve the cake with the remaining sauce.