Step 1

Rub the inside of your baking dish with butter or brush oil all over. Add about 1 TBSP of flour and dust the whole dish. Discard any excess flour.

Step 2

Preheat your oven to 350˚ F.

Step 3

In a medium mixing bowl, whip the room temperature butter with a handheld mixer until very fluffy.

Step 4

Add the sugar and mix on high speed for 3-5 minutes.

Step 5

Add one egg at a time, mixing the batter on high speed after each addition.

Step 6

Add the juice of about 1 ½ lemons, about 1 teaspoon of lemon zest, a few drops of lemon essential oil (if using), flour, baking powder, and the sourdough starter. Gently mix on low until combined. Do not over-mix!

Step 7

Transfer the dough to the glass baking dish and spread it evenly (with a rubber spatula).

Step 8

Bake for 35-50 minutes or until an inserted toothpick comes out clean.

Step 9

Use the same toothpick to poke a lot of holes in the cake.

Step 10

For the glaze, mix the juice of the remaining 1 ½ lemons, powdered sugar to taste, and a few drops of lemon essential oil (if using). Spread the glaze evenly over the cake.