INGREDIENTS
2 cups
all-purpose flour
2 1/2 cups
granulated sugar
3/4 cup
Dutch process cocoa (I used Valrohna)
2 tsp
baking soda
1 tsp
kosher salt
1 cup
vegetable or canola oil
1 cup
full fat sour cream
1 1/2 cups
water
2 tbsp
distilled white vinegar
1 tsp
vanilla extract
2
large eggs, at room temperature
4 oz
egg whites
4 oz
sugar
1/4 tsp
kosher salt
3 sticks
(12 ounces/339 grams)unsalted butter, cut into 2 inch chunks and at room temperature
1 tsp
pure vanilla extract
1/2 cup
Speculoos or Biscoff Cookie Spread
1/4 cup
+ 2 tablespoons unsweetened Dutch-process cocoa powder (I used Valrohna)
1/4 cup
+ 2 tablespoons boiling water
1 1/2 cups
(3 sticks/341 g) unsalted butter, room temperature
1/2 cup
powdered sugar
salt
1 lb
good-quality semi-sweet chocolate, melted and cooled
Chocolate sprinkles for garnish