Preheat your oven to 350°F (175°C) and lightly grease a donut pan.

In a large bowl, whisk together the flour, granulated sugar, baking powder, salt, and cinnamon.

In another bowl, combine the milk, egg, melted butter, and vanilla extract.

Pour the wet ingredients into the dry ingredients and mix until just combined, being careful not to overmix.

Spoon the batter into the prepared donut pan, filling each cavity about 2/3 full.

Bake for 10-12 minutes, or until the donuts are lightly golden and a toothpick inserted in the center comes out clean.

Allow the donuts to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.

While the donuts cool, whip the heavy cream until soft peaks form.

Once the donuts are cool, spread a thin layer of whipped cream on top of each donut.

Sprinkle a teaspoon of brown sugar evenly over the whipped cream.

Using a kitchen torch, carefully caramelize the brown sugar until it forms a crispy crust. Alternatively, place the donuts under the broiler for 1-2 minutes, watching closely to prevent burning.

Serve immediately for the best texture.