Cinnamon Swirl Whole Grain Sourdough Coffee Cake

Directions

1. Preferment
2. Mix milk and cream together. Add flour and starter to a medium bowl, and pour about 2/3 of the dairy in (I eyeball it here). Mix until you fully hydrate the flour, or add more liquid as needed to do so. The preferment should be evenly mixed, fully hydrated, but firm and not sticky. Depending on the hydration of your starter and your flour, you may have to use a little more or less liquid than I've listed.
3. Cover and let ferment. If making cake that day, it can be at room temperature for a few hours (about 3 hours for me), until it’s risen a little. Since it’s so firm, it won’t rise much, and should not double. If making later, cover and refrigerate for about a work day or overnight. If making the cake later, the preferment can be made the morning of, and the cake finished in the evening. You can also make the preferment the evening before you make the cake, and finish the cake the next day.

1. Final Cake
2. If you’re like me and always forget to take ingredients out of the fridge to warm, toast the walnuts while you’re waiting to take the chill off the preferment and butter. Preheat oven to 250F, spread the walnut pieces on a baking sheet, and bake until fragrant, about 10min. Remove from heat and turn off oven. Let nuts cool. If you’re on top of your mise en place, disregard this step.
3. Oil or butter a 12 cup bundt pan, set aside
4. Mix nuts, brown sugar, cinnamon and cocoa powder in a small bowl, set aside.
5. Put preferment and sugar in the bowl of a stand mixer. Sprinkle in salt and yeast. With the paddle attachment, mix on medium-low to incorporate. Mix will be dry and sandy at first, but then come together around the paddle. This should only take a minute or 2.
6. With mixer running, add eggs one at a time, letting each one mix in before adding the next. Add the vanilla with the last egg.
7. Add the butter in a few additions, letting each incorporate before adding more. This doesn’t have to be very precise, 3-4 additions of butter is what I do.
8. Mix until the batter is smooth and evenly mixed, that is sufficient. Using a rubber spatula, scrape from the bottom once or twice to ensure the batter is evenly mixed. The crumb structure comes from fermentation, not from creaming the ingredients, so don't over mix. The cake batter should be smooth and scoopable (not pourable), similar to a muffin batter or maybe a little thicker.
9. Scoop about 1/3 of the batter into a prepared bundt pan and smooth it into an even layer. Sprinkle ½ of the nut spice mix on top. Scoop another 1/3 of batter on top of the nuts, smoothing it with the spatula (and maybe your fingers) to cover the nuts. Sprinkle the rest of the nut spice mix. Scoop the rest of the batter into the pan and smooth it out. The pan should be a little over half full.
10. Cover the pan and let the batter rise until about 1 ½ inches from the top of the pan. This will vary based on how warm your space is, but in my kitchen, this normally takes about 2 ½ -3 hours.
11. Preheat the oven to 350F for about 20 minutes.
12. Bake cake, uncovered, until it reaches an internal temperature of 200F, or until a toothpick comes out with only a few crumbs if you don't have a thermometer, which is in about 45 minutes in my oven. Avoid opening the oven door for the first 30 minutes of baking. The cake does not have much oven spring, and should only rise to the top of the pan. The visible part of the cake will get a golden color, and will form a crust (I know I said this cake is not bready, and it’s not, trust me). This will soften and become tender once the cake is turned out of the pan.
13. Once the cake is done, remove from oven and let cool in the pan for 10 -15 minutes. Try not to forget about it because sugar from the nut mix could stick to the pan if it cools too much.
14. Turn the cake out of pan, and let cool completely.
15. Slice and serve for breakfast, dessert, or a quick bite with coffee or tea!