Begin by making the ginger dough. In a medium bowl, add the flour, ginger, cinnamon, salt, nutmeg and allspice, stir with a whisk to combine.
Add 1/4 cup butter and the brown sugar to a large bowl. Beat with a mixer on medium until well combined.
You will end up using an entire egg in this recipe. To remove the yolk from the egg white, crack the egg over a bowl carefully. Split the two ends of the egg and move the egg from shell piece to shell piece until the white falls into the bowl and the yolk is left in the shell. Reserve the egg white for the lemon dough.
Add molasses and egg yolk to the sugar and butter. Beat until well blended.
Add flour mixture to butter mixture; beat at low speed just until combined.
Wrap dough in plastic wrap and refrigerate for 30 minutes.
To make the lemon dough, add 5 tablespoons softened butter and the sugar in a large bowl. Mix at medium speed until blended. Add the egg white and beat until combined.
Add lemon rind, 1/2 teaspoon lemon juice, and vanilla using a mixer to blend.
In a medium sized bowl, combine the flour and salt. Add flour mixture to butter mixture and beat at low speed just until combined. Wrap dough in plastic wrap; chill 30 minutes.
Unwrap ginger dough. Roll ginger dough between sheets of plastic wrap into a 13 x 8 1/2–inch rectangle (3/16 inch thick). (I honestly just eyeballed this). Chill 10 minutes.
Unwrap lemon dough. Roll lemon dough between sheets of plastic wrap into a 13 x 9–inch rectangle (3/16 inch thick). Basically I just tried to make it slightly thinner than the ginger dough. It doesn’t have to be perfect. Chill 10 minutes.
Carefully stack ginger dough on top of lemon dough, leaving a 1/2-inch border along one long edge.
Starting with the long side without a border, roll up dough, jelly-roll fashion. Seal edges (do not seal ends of roll). Cover with plastic wrap; freeze 30 minutes.
Remove the dough from the freezer. Preheat your oven to 350 degrees. Unwrap dough. Cut with a sharp knife into 40 slices.
Arrange slices 1 inch apart on baking sheets lined with parchment paper.
Bake one batch at a time for 9 minutes. Cool on wire racks.
Notes
If you make this recipe, share a photo on Instagram and tag me @icancookthat!