Pre-heat the oven to 350℉ and line 2 cupcake pans with paper liners or spray with non stick spray. Set aside.
In a large bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a separate bowl, whisk together the biscoff, brown sugar, sour cream, milk, oil, egg, and vanilla until well combined and no lumps of biscoff are left.
Make a well in the dry ingredients and pour the wet ingredients into the dry. Mix together until combined.
Scoop the batter into the muffin liners, filling about ¾ of the way full.
Bake the cupcakes for 20-23 minutes, or until a toothpick comes out clean. Allow them to cool in the pan for 5-10 minutes, and then remove them to cool completely on a wire cooling rack.
Make the biscoff buttercream
Combine butter and biscoff in a large bowl and use a stand mixer with a paddle attachment or a hand mixer to beat until creamy and well-combined.
With the mixer on low speed, gradually add the powdered sugar until completely combined, scraping the sides of the bowl as needed.
Stir in vanilla extract and salt. With the mixer on low speed, add 1 tablespoon of milk and mix until combined. Add 1-2 more tablespoon of milk as needed. Gradually increase speed to high and beat for another 30 seconds to 1 minute.
Pipe or spread the frosting onto completely cooled cupcakes.
Notes
Make sure to use room-temperature ingredients for both the cupcakes and the buttercream. It’ll make it easier for them to combine and give you fluffier cupcakes!
Don't overmix the cupcake batter once you add the dry ingredients, that can give you muffins that sink in the middle!
Make sure you don’t overfill your cupcake liners or the batter will overflow in the oven! I fill mine about ¾ of the way full.
Decorate the frosted lotus cupcakes with biscoff cookies or crushed biscoff cookies, or even drizzle extra cookie butter on top!
If you want to make these cupcakes ahead of time, bake the cupcakes, and once they cool store them in an airtight container for up to one day before.