Preheat the oven to 375 degrees F. Lightly spray a 11x15-inch rimmed pan. Line the bottom only with parchment paper. Spray the parchment paper lightly with nonstick spray.
MAKE THE CAKE:
Sift the flour (again) with salt, soda and spices; set aside.
In a large bowl, use an electric mixer at high speed to beat the eggs until thick and lemon-colored (3 to 4 minutes). Gradually beat in the sugar a little at a time, beating well after each addition. Beat until the mixture is very thick and light, about 5 minutes. At low speed, blend in the flour mixture until smooth. Add the molasses; beat until combined. Pour the batter into the prepared pan, spreading evenly. Bake 12 to 15 minutes, or just until the surface springs back when gently pressed with fingertips.
Next is the most crucial part of the whole cake roll process: As soon as you pull the cake out of the oven, turn it out onto a tea towel lightly dusted with powdered sugar. Peel off the parchment paper. Trim the edges of the cake so it's nice and even. Then, starting at one of the short ends, roll the cake up into the towel—yes, you want the towel to be rolled up inside. Allow the cake to cool completely on a wire rack. This will help train the cake to roll up nicely later once its filled.
ADD THE FILLING:
When the cake has cooled, gently unroll and remove the towel. Spread the cake with ice cream and re-roll. Wrap the cake roll with plastic wrap and freeze for 4 hours, or until ready to serve.
SERVE:
Before serving, sift additional powdered sugar over the top of the roll, if desired. Cut into slices to serve.
Notes
Option: fill with cream cheese filling instead of ice cream: In a large bowl, use an electric mixer to beat a package of softened cream cheese, a quarter cup of butter (also softened) along with a cup of powdered sugar and a half teaspoon of vanilla extract together until fluffy. Spread on the cooled cake and roll up. You can keep it in the refrigerator instead of the freezer.