Preheat oven to 350°F (175°C). Grease and flour a cake pan.

In a large bowl, cream shortening and sugar until light and fluffy.

Add eggs, one at a time, beating well after each addition.

Beat in the red food coloring, vinegar, and vanilla extract.

In a separate bowl, combine cake flour, cocoa, salt, and baking soda.

Add the dry ingredients to the creamed mixture alternately with buttermilk, beating well after each addition.

Pour batter into the prepared cake pan.

Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.

Cool the cake on a wire rack completely.

For the sauce, in a small saucepan, combine sugar and cornstarch.

Stir in the orange juice until smooth.

Add the blueberries, nutmeg, and salt to the saucepan.

Cook and stir over medium-high heat until thickened and bubbly.

Reduce heat to low and cook, stirring constantly, for 2 minutes longer. Cool the sauce.

In a small bowl, whip heavy cream and confectioners' sugar until stiff peaks form.

Serve the cake with the blueberry sauce and whipped cream.