Preheat the oven to 350°F (180°C).

Core the apples using an apple corer, making sure to leave the bottom intact.

In a medium-sized pot, combine the sugar, water, and vanilla extract, and bring it to a boil.

Add the cored apples to the pot, and reduce the heat to low. Cover the pot and let it simmer for 10-15 minutes, or until the apples are tender.

Remove the apples from the pot and let them cool down.

Meanwhile, toast the chopped walnuts in the preheated oven for 5-10 minutes, or until they are lightly golden.

Once the apples have cooled down, spoon some of the syrup from the pot into the core of each apple.

Stuff the apples with the toasted walnuts.

In a separate bowl, whip the heavy cream until it forms stiff peaks.

Serve each apple with a dollop of whipped cream on top, and a sprinkle of cinnamon powder.