This pumpkin cake starts out with melted butterscotch chips and just gets better from there. It is moist and chewy and almost brownie-like, except for the copious amounts of creamy vanilla frosting on top. This is pumpkin dessert at its finest, my friends.
Preheat your oven to 350 degrees F. Line an 8x8 inch square pan with parchment paper, or grease well. Set aside.
In a large microwaveable mixing bowl, add butterscotch chips and butter. Melt in the microwave in 30 second increments until the mixture is smooth. (It may take a bit of stirring; see photos below. I used a whisk toward the end.)
Use a wooden spoon to stir in the sugar and pumpkin puree.
Add the flour to the bowl, but don't mix it in yet. Add the cinnamon, pumpkin pie spice, and salt, and stir that into the flour with a dry spoon. Then stir the flour into the rest of the mixture. Don't overmix, just stir until it's combined.
Spread the batter into the prepared pan. Bake in the preheated oven for 27-29 minutes, or until a toothpick comes out clean. Let the cake cool completely.
Meanwhile, make the frosting. In a mixing bowl, beat the butter for about 1 minute until it is fluffy. (If you haven't softened it, make it 2-3 minutes.)
Add 1 cup of the powdered sugar and combine. Add the vanilla and 3 teaspoons of milk.
Beat in the remaining powdered sugar. Add a little more milk if it is stiff. Add a dash of salt if it is too sweet for you.
Beat well, scraping down the sides, before spreading it on the top of the cooled cake.
Sprinkle with additional pumpkin pie spice, if desired.
This cake is really easy to double and bake in a 9x13 inch pan. Also, this is a generous amount of frosting; you may not need all of it. (I mean, I do, but that's me.) If you are doubling the cake, I would only make 1 1/2 the amount of frosting: 3/4 cup (1 and 1/2 sticks) salted butter, 2 1/2 cups + 2 tablespoons powdered sugar, 1 and 1/2 teaspoons vanilla bean paste (or regular vanilla), about 2-3 tablespoons milk, and a pinch of salt, if you want.Source: The Food Charlatan. Melted chip idea from these Lemon Lemonies by Averie Cooks.