Preheat the Oven & Prepare Pan

• Set your oven to 350°F (≈ 175°C).

• Grease a deep baking dish—9×9×3‑inch or 9×11×3‑inch works well—using nonstick spray or butter and flour.

2. Mix the Wet Ingredients

• In a mixing bowl, cream together granulated sugar, brown sugar, and butter with a hand mixer or stand mixer. Beat ~3 minutes until light and fluffy.

• Add eggs one at a time, beating after each until well combined. Then stir in vanilla extract, pumpkin puree, maple syrup, and buttermilk. Mix until smooth and homogenous.

3. Prepare the Dry Ingredients

• In a separate bowl, whisk together flour, baking powder, baking soda, kosher salt, and pumpkin spice. Ensure spices are well distributed.

4. Combine Wet & Dry

• Gradually pour or spoon the dry mixture into the wet ingredients, mixing gently until no streaks of flour remain. Don’t overmix—just enough to combine.

5. Bake the Cake

• Pour batter into the prepared dish, smoothing the top.

• Bake for 45–55 minutes, or until a toothpick inserted in the center comes out clean and the cake no longer jiggles. The center should be set though the cake remains moist and dense.

• If the top starts to brown too quickly, tent it loosely with foil midway through baking to prevent over-browning.

6. Cool the Cake

• Remove from oven and allow it to cool in the pan (on a rack) for at least 15‑20 minutes before handling further.

7. Make the Toffee Sauce

• While the cake is baking (so timing overlaps), in a medium saucepan over medium‑low heat melt butter and brown sugar together, stirring constantly for about 10 minutes until well combined and sugar dissolves.

• Add heavy cream and vanilla extract, continue cooking ~5 minutes more, stirring, but avoid boiling. You want it to be silky and smooth. If bubbles get too large or it begins to boil, reduce the heat.

8. Assemble the Cake with Toffee

• Once the cake has cooled (but still slightly warm maybe), poke holes all over the top using a toothpick or skewer.

• Slowly pour the toffee sauce over the top, letting it soak into the holes.

• Let cake rest at least 1 hour (longer is even better, e.g. overnight) so the sauce fully absorbs.

9. Serve!

• Slice and serve as desired. Warm or room temperature both work. Optional: with whipped cream, ice cream, or a dusting of cinnamon.