Preheat oven to 180C and line your cupcake tins with cupcake liners.
Finely grind the graham crackers (digestive biscuits) in a grinder and sift it together in a bowl with flour, baking powder, baking soda and salt. Keep this dry mixture aside.
In a glass, mix in buttermilk, yoghurt and vanilla and keep this wet mixture aside.
In a separate bowl, add in butter, sugar and brown sugar, and beat it using a hand mixer (or simply a whisk) until light and fluffy.
Turn the speed to low, and mix in the eggs, one at a time.
Next, alternatively, add in the dry and mix until fully incorporated.
Pour this batter into your lined cupcake tins, 2/3 way full.
Bake for 20-25 minutes, or until a toothpick inserted comes clean.
Let them cool completely before frosting.