Preheat oven to 350 degrees F (175 degrees C). Grease a 9-inch round or square pan and line bottom with parchment paper.

Whisk flour, cinnamon, ground ginger, baking soda, baking powder, and salt together in a large bowl.

Beat butter and brown sugar together in another large bowl with an electric mixer until light and fluffy, 3 to 4 minutes. Add corn syrup, molasses, and egg; beat until smooth. Pour in hot water slowly while continuing to beat. Add flour mixture gradually, mixing until batter is well-blended and smooth. Stir in crystallized ginger. Pour batter into the pan.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, 30 to 35 minutes. Cool in the pan, about 10 minutes. Run a knife around the edges and carefully invert onto a wire rack. Cut into wedges or squares.

Whip heavy cream and maple syrup together in a large bowl until stiff peaks form. Serve whipped cream topping with cake.