Preheat the oven to 350 degrees. Line two muffin tins with paper liners and set aside.
Combine the sugar and vanilla paste in the bowl of an electric mixer fitted with the paddle attachment.
Mix at low speed until the paste combines with the sugar and is fragrant, about one minute.
Add the butter in small pieces, about 1 tablespoon, and continue to mix at a low speed until fully incorporated and fluffy, about 2 minutes.
Slowly stir in the eggs, yogurt, oil, and extract. Mix for 1 minute, scraping the sides halfway through to ensure even mixing.
In a separate bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt.
Slowly stir into the wet ingredients along with the milk, making sure to keep the mixer at low speed and scraping the sides of the bowl 1 to 2 times.
Fill the paper liners until they are filled halfway.
Bake for 14 minutes or until a toothpick comes out clean.
Cool completely before filling and frosting.
Once cooled, core the cupcake and fill with 1 tablespoon of filling.
Press the removed cupcake piece on top to secure firmly over the sauce.