Preheat oven to 350 degrees. Line 2 12-cup muffin tins with parchment liners.
Make the caramel. Melt the sugar in a small saucepan, whisking constantly, until completely liquified and golden brown, about 4-5 minutes. Add the butter and stir until melted - be careful, it WILL splatter. Pour in the heavy cream and simmer until thickened, about 2-3 minutes. Remove pan from the heat and stir in the vanilla and kosher salt. Let cool.
In a large bowl, beat the butter and sugar for 2-3 minutes until light and fluffy. Whip in the eggs, one at a time, then the vanilla and yogurt. Add the flour, baking powder, baking soda, and salt. With the mixer running, stream in the buttermilk until the batter is just combined. Do not overmix.
Fill each cupcake tin 2/3 of the way with batter. Depending on what your heart says 2/3 of the way full is, you will get 22-24 cupcakes. Bake for 25-30 minutes until an inserted toothpick emerges with just a few moist crumbs. Cool 10 minutes in the pans, then transfer the cupcakes to wire racks. Cool completely.
Using a spoon, remove about 1 teaspoon of cake from the center of each cupcake. Scoop 1 teaspoon of caramel into the gap. If the caramel has thickened too much, heat in a microwave-safe bowl for 15-20 seconds to soften.
Make the frosting. Whip the butter, caramel, and vanilla until combined, then add the powdered sugar and 1/4 cup of cream. Crank the mixer to high, and beat until very light and fluffy, about 2-3 minutes. You may need an extra tablespoon of two of cream to achieve the desired texture. Scrape down the sides of the bowl with a spatula, as needed, to properly incorporate all the ingredients.
Pipe or frost each cupcake with the buttercream. Drizzle with more caramel and top with a cute lil stroopwafel!