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Lawrence D. Smith

Soft-Baked Cinnamon Donut Cake

A light and fluffy sour cream butter cake coated inside and out with cinnamon sugar for a sweet, warmly spiced, donut-inspired finish.
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Prep Time 15 minutes
Cook Time 50 minutes
Total Time 1 hour 5 minutes
Servings: 16
Course: Dessert
Cuisine: American
Ingredients Equipment Method Notes

Ingredients
  

Cinnamon Sugar
  • 60 g raw or turbinado sugar
  • ½ teaspoon cinnamon
Donut Cake
  • 150 g unsalted butter at room temperature
  • 320 g granulated sugar
  • 1 tablespoon vanilla extract or vanilla bean paste
  • 2 large eggs about 110 g without shells, at room temperature
  • 165 g sour cream at room temperature
  • 250 g all-purpose flour
  • ¾ teaspoon baking powder
  • ½ teaspoon kosher salt use less if using table salt or salted butter
  • ¼ teaspoon cinnamon

Equipment

  • 8-inch (20 cm) square baking pan, preferably non-stick
  • Small bowl
  • Medium mixing bowl
  • Large mixing bowl or stand mixer bowl
  • Stand mixer fitted with a paddle attachment or electric hand mixer
  • Measuring scale and/or measuring spoons
  • Rubber spatula
  • Spoon for smoothing the batter
  • Skewer or cake tester
  • Plastic knife or scraper for slicing, especially when using a non-stick pan

Method
 

  1. Prepare the Oven and Cinnamon Sugar: Preheat the oven to 330°F (165°C). In a small bowl, combine the raw or turbinado sugar and ½ teaspoon cinnamon.
  2. Coat the Baking Pan: Generously grease an 8-inch (20 cm) square baking pan with butter. Add the cinnamon sugar mixture and coat the bottom and all sides of the pan generously.
    Shake any remaining cinnamon sugar back into the bowl and reserve it for topping the cake. Place the prepared pan in the refrigerator until ready to use so the butter can firm up and remain in place when the batter is added.
  3. Cream the Butter and Sugar: In the bowl of a stand mixer or a large bowl using an electric mixer, beat the room-temperature butter, granulated sugar, and vanilla on medium-high to high speed until the mixture is very light and fluffy.
  4. Add the Eggs: Add the eggs one at a time, mixing well after each addition. Once both eggs have been incorporated, continue beating on high speed for 2 to 3 minutes, until the mixture has thickened and become very light.
  5. Prepare the Remaining Ingredients: Measure the sour cream into a small bowl. In a separate medium bowl, combine the all-purpose flour, baking powder, kosher salt, and ¼ teaspoon cinnamon.
  6. Combine the Batter: Alternately add the flour mixture and sour cream to the butter mixture, beginning and ending with the flour. Add the flour mixture in three additions and the sour cream in two additions, mixing briefly between each addition.
    Switch to a spatula and gently turn the batter a few times to ensure everything is evenly combined.
  7. Fill the Pan: Transfer the batter to the chilled, cinnamon-sugar-coated pan. Smooth the surface with a spatula or the back of a spoon, making sure there are no large air bubbles in the batter.
  8. Add the Cinnamon Sugar Topping: Sprinkle the reserved cinnamon sugar evenly over the top of the batter.
  9. Bake the Cake: Bake for 45 to 50 minutes. The cake is ready when the center springs back lightly when pressed with a finger and a skewer inserted into the middle comes out clean or with only a few moist crumbs attached.
  10. Cool and Slice: Remove the cake from the oven and allow it to cool in the pan. If using a non-stick pan, slice the cake with a plastic knife or scraper to avoid damaging the pan.
  11. Store and Reheat: Store the cake in an airtight container at room temperature for up to 4 days. If serving after the day it was baked, microwave individual portions briefly to re-warm and freshen the cake.

Notes

  • Use an 8-inch (20 cm) non-stick square cake pan for the method as tested in the original recipe. The recipe was not tested in a glass pan or a non-stick alternative.
  • Generously coat every side of the buttered pan with the cinnamon sugar mixture to create the characteristic cinnamon-sugar exterior.
  • Refrigerating the prepared pan before adding the batter helps the butter firm up, reducing the chance of the cinnamon-sugar coating coming away from the sides.
  • Make sure the butter, eggs, and sour cream are at room temperature as specified for smoother mixing and a light, fluffy batter.
  • Beat the butter, sugar, and vanilla until very light and fluffy, then continue beating after the eggs have been added for the full 2 to 3 minutes described in the recipe.
  • Add the flour mixture and sour cream alternately, beginning and ending with the flour mixture, and avoid excessive mixing.
  • Check for doneness by lightly pressing the center and inserting a skewer into the cake. It should spring back and the skewer should come out clean or with a few moist crumbs.
  • Store leftovers in an airtight container at room temperature for up to 4 days.
  • To freshen leftover cake, briefly warm individual portions in the microwave before serving.
  • For a jam variation, omit the cinnamon from both the sugar coating and the cake batter. Once the batter is in the pan, make small divots with a teaspoon, fill them with jam, gently cover the jam with batter, and then sprinkle the top with sugar. The original variation used 150 g raspberry fruit preserve.