Step 1

Preheat oven to 350°. Beat shortening, sugar, molasses and eggs until well blended. Combine next five ingredients; add to molasses mixture alternately with hot water.

Step 2

Pour into a greased 13x9-in. baking pan. Bake until a toothpick inserted in center comes out clean, 35-40 minutes. Cool on a wire rack.

Step 3

Meanwhile, for lemon sauce, combine first five ingredients in a small saucepan until smooth. Cook and stir over medium-high heat until thickened and bubbly. Reduce heat; cook and stir 2 minutes longer. Remove from heat.

Step 4

Stir a small amount of hot filling into egg yolks; return all to pan, stirring constantly. Bring to a gentle boil; cook and stir 2 minutes longer. Remove from heat. Gently stir in butter, lemon juice and zest, increasing juice if needed to thin sauce. Serve with warm cake. Refrigerate leftover sauce.