Preheat the oven to 350°F (175°C). Grease and flour a 9x13-inch baking dish.

In a medium bowl, sift together the flour and baking powder. Set aside.

In a large bowl, cream together the butter and 1 cup sugar until light and fluffy. Add eggs one at a time, beating well after each addition. Stir in ½ teaspoon vanilla.

Gradually mix in the flour mixture, alternating with the whole milk. Beat until smooth.

Pour the batter into the prepared baking dish. Bake for 30 minutes, or until a toothpick inserted into the center comes out clean.

In a separate bowl, combine the condensed milk, evaporated milk, and ¼ cup of the heavy cream. Once the cake is baked, poke holes all over the surface with a fork, then slowly pour the milk mixture over the cake, allowing it to soak in.

Refrigerate the cake for at least 1 hour to allow it to absorb the milk mixture fully.

In a chilled bowl, whip the remaining heavy cream with 1 tablespoon sugar and 1 teaspoon vanilla until stiff peaks form. Spread over the chilled cake and sprinkle with ground cinnamon before serving.