Apple Crumb Cake with Sour Cream & Sourdough Discard

We were headed to a potluck with one of The Hubs' Homebrew Groups, and I needed something to use this week's sourdough discard in. We also had a container of sour cream that needed to get used up, and some of last year's apples from our backyard tree hanging out in the freezer.  When I searched the interwebz for a "sourdough sour cream apple cake"...I got a lot of "sourdough apple cakes" and "sour cream apple cakes"...but no crossover.  So--I found a couple different recipes I liked, mixed & matched, and this was the end result.

Note: This results in some of the measurements below being in grams, and some in dry measurements--this is because the sourdough substitution is based on weight, rather than volume--I removed 75g of flour and 75g of sour cream from the cake layer to make up for the addition of the 150g of sourdough discard.

INGREDIENTS:

Apple Layer:

• 3 cups frozen or fresh sliced apples, peeled (sliced thin or cubed)
• 2/3 cup sugar
• 1 Tbsp butter
• 1.5 Tbsp lemon juice
• 2 tsp cinnamon
• 1/2 tsp nutmeg

Cake Layer:

• 1.5 sticks unsalted butter, room temp
• 3/4 cup sugar
• 170g sour cream (about 2/3 cup)
• 3 eggs
• 2 tsp vanilla extract
• 150g sourdough discard
• 240g all-purpose flour (should be a little shy of 2 cups)
• 1 tsp baking soda
• 1 tsp baking powder
• 1 tsp salt

Crumb Topping:

• 1 stick unsalted butter, melted
• 3/4 cup flour
• 1/2 cup quick oats
• 1/2 cup brown sugar
• 1/4 cup white sugar 
• 2 tsp cinnamon
• 1/4 tsp salt
• 1/2 cup pecans, crushed

DIRECTIONS:

1. Preheat the oven to 350F.
2. In a medium saucepan, combine the APPLE LAYER ingredients and bring to a boil.  Lower the heat and let simmer until apples are very soft, around 20 minutes.  Remove from heat--it will continue to thicken as it cools.
3. In a separate medium bowl, melt the butter for the CRUMB TOPPING, then add the remaining ingredients and mix with a fork until crumbly.  Set aside.
4. Using a large bowl and hand mixer, or a stand mixer, combine the room temp butter and sugar and beat until fluffy. Then add the eggs, sour cream, vanilla, and sourdough discard and mix until smooth.
5. Remove the bowl from the stand mixer and weigh the flour into the bowl, then add the salt, baking powder and baking soda. Place back on the mixer and blend until combined.
6. Pour CAKE LAYER into a buttered 9x13 pan and smooth out.  Then add the APPLE LAYER onto the cake batter, and use a butter knife to swirl the mixture evenly into the CAKE LAYER.
7. Add the CRUMB TOPPING layer evenly across the top of the pan, and bake for 40-45 minutes.

Cake Layer.

Apple Layer added & swirled in.

Crumb Topping added.

This works well as a dessert, or as a coffee cake for breakfast!