Preheat the oven to 350º Fahrenheit.

Spray a 9” square cake pan with cooking spray.

In a medium bowl, combine the flour and sugar.

Cut the butter into chunks, then add to the flour and sugar mixture. Use a pastry cutter to cut the butter in until the mixture resembles coarse crumbs.

Press half of this mixture into the prepared pan.

Add the baking soda and nutmeg to the remaining crumb mixture. Mix well.

Mix in the egg and sour cream.

Spread this mixture over the crumb cake base.

Sprinkle with pecans.

Bake for 35 minutes or until a toothpick inserted into the center comes out clean.

While the cake is baking, make the lemon sauce.

Combine the sugar, cornstarch and salt in a saucepan. Mix well.

Stir in the water and lemon juice. Heat and stir over medium heat until the mixture thickens and comes to a boil. Boil for 1 minute, then remove from the heat.

Stir in the lemon zest, mace and butter. Stir until the butter is melted.

Serve the cake warm with lemon sauce over the top and a dollop of whipped cream.