Preheat the oven to 350°F (175°C). Line a 12 cup muffin pan with parchment liners. Have additional liners ready, as this recipe makes about 15 cupcakes.

Add the cane sugar and lemon zest to a large mixing bowl. Rub the zest into the sugar with your fingers until fragrant.

Add the eggs, milk, lemon juice, vanilla extract, sour cream, and olive oil. Whisk until smooth and well combined.

In a separate bowl, whisk together the khorasan flour, all purpose flour, baking powder, sea salt, and baking soda.

Add the dry ingredients to the wet ingredients and gently mix until just combined. Do not overmix.

Divide the batter between the prepared liners, filling each about ¾ full.

Bake for 15 to 18 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached.

Allow the cupcakes to cool in the pan for several minutes before transferring them to a wire rack to cool completely.

To make the buttercream, beat together the softened butter, heavy cream, lemon juice, lemon zest, vanilla bean paste, and sea salt until smooth and creamy.

Gradually add the powdered sugar and continue mixing until light and fluffy. Add additional powdered sugar if needed for sweetness or a thicker consistency.

Once the cupcakes have cooled completely, frost as desired and garnish with additional lemon zest if desired.