First, make the cupcakes. Preheat oven to 350F and line two muffin pans with 18 muffin liners.

In a small bowl, whisk together the ground flaxseed with the water and set aside to thicken.

In the bowl of a stand mixer, combine the flour, baking powder, baking soda, salt, and sugar.

Add in the vegan butter, and beat on low until it's incorporated and has a sandy texture.

In a small bowl, whisk together the oil, flaxseed mixture, nondairy yogurt, lime zest, key lime extract and vanilla extract, and add them to the dry ingredients. Mix until combined.

Pour in the unsweetened nondairy milk and key lime juice, and beat on medium-low until smooth and creamy.

Divide batter evenly among the prepared cupcake liners. Bake cupcakes for 20-25 min until they are fluffy and a toothpick inserted in the center comes out clean.

While the cupcakes cool, prepare the frosting.

In the bowl of a stand mixer, beat the shortening, vegan butter, lime juice, key lime extract and vanilla extract together until completely smooth and creamy. Add in the powdered sugar, 1 cup at a time, until a thick frosting forms. You can add a few spoonfuls of nondairy milk if it's too thick.

When your cupcakes have cooled, frost as desired (I used an 8B tip) and top with an extra sprinkle of lime zest and a piece of sliced lime. Enjoy!