Step 1

Preheat oven to 375 degrees F.

Step 2

Stir together milk and lemon juice, set aside. (This is a like a faux buttermilk.)

Step 3

Use mandoline (or very sharp knife) to cut your apple wedges into paper thin slices. Then run your knife through them vertically to cut into sticks, then horizontally so the sticks are kind of like rectangles. This doesn't have to be perfect, you're just trying to make the pieces smaller.

Step 4

To a large mixing bowl, add brown sugar, egg, and sourdough discard. Whisk together until homogenous. Add oil, milk mixture, and vanilla. Whisk again to combine.

Step 5

To a small bowl, add flour, baking powder, salt, and nutmeg. Whisk.

Step 6

Add flour mixture to wet ingredients, and use a spatula to stir until about half combined. Then add apples and fold in to distribute, just until no flour streaks are left. Be sure to not overmix.

Step 7

Scrape batter into a greased or parchment lined 8x8 baking pan (do not use glass). Use back of spoon to even out the batter. The mix topping ingredients together and evenly sprinkle over the cake.

Step 8

Turn OVEN DOWN to 325 degrees F and bake for 35 to 38 minutes, until toothpick comes out with a few moist crumbs, but not wet. Let cool and serve.