Makes 32 sandwich cookies
For the dough:
- 2 cups all-purpose flour
- 1 tablespoon ground ginger
- 2 1/2 teaspoons ground cinnamon
- 1 3/4 teaspoons baking soda
- 1/4 teaspoon fine salt
- 1/3 cup plus 3/4 cup granulated sugar
- 12 tablespoons unsalted butter (1 1/2 sticks), at room temperature
- 1 large egg, at room temperature
- 1/4 cup plus 2 tablespoons blackstrap molasses
- 2 tablespoons finely chopped crystallized ginger
For the filling:
- 2 1/2 cups powdered sugar, sifted
- 6 tablespoons unsalted butter (3/4 stick), at room temperature
- 1 tablespoon finely grated lemon zest (from 1 medium lemon)
- 1 tablespoon lemon extract
- 1 tablespoon freshly squeezed lemon juice (from 1 medium lemon)
- Heat the oven to 160°C (325°F) and arrange the racks to divide it into thirds. Line 2 baking sheets with parchment paper; set aside.
- Combine the flour, ground ginger, cinnamon, baking soda, and salt in a large bowl and whisk to break up any lumps; set aside.
- Place 1/3 cup of the sugar in a small bowl; set aside.
- Place the remaining 3/4 cup of sugar and the butter in the bowl of a stand mixer fitted with a paddle attachment. Mix on medium speed until lightened in color and fluffy, about 2 minutes. Stop the mixer and scrape down the sides and bottom of the bowl with a rubber spatula.
- Return the mixer to medium speed, add the egg and molasses, and beat until smooth, about 1 minute. Stop the mixer and scrape down the sides and bottom of bowl. Turn the mixer to low speed, add the reserved flour mixture, and mix until the dough just comes together, about 30 seconds. Add the crystallized ginger and mix until just incorporated, about 10 seconds more.
- Place half of the dough on a piece of plastic wrap, wrap tightly, and refrigerate.
- Divide the remaining dough in the mixer bowl into 2 portions.
- Divide 1 of the portions into 16 rough pieces (each about 1 heaping teaspoon) and place on 1 of the prepared baking sheets.
- Using your hands, gently roll each piece with your fingers to form a ball. Roll the dough balls in the reserved sugar until coated all over, then evenly space them on the baking sheet; set aside.
- Repeat with the remaining dough in the mixing bowl and the second baking sheet.
- Place both sheets in the oven and bake for 6 minutes. Rotate the baking sheets front to back and top to bottom and bake until the cookies are dry to the touch and are set at the edges, about 5 to 7 minutes more. (The cookies will still be soft.)
- Immediately remove the cookies to a wire rack and let cool completely. Reserve the parchment paper and let the baking sheets cool for 5 to 10 minutes. Repeat with the remaining dough portion in the refrigerator.
For the filling:
- Place the powdered sugar, butter, and zest in the bowl of a stand mixer fitted with a paddle attachment and mix on low speed until the mixture looks crumbly. Gradually increase the speed to medium and beat until smooth, about 2 minutes. Reduce the mixer speed to low, add the lemon extract and juice, and beat until combined, about 30 seconds. Increase the speed to medium and beat until fluffy, about 1 minute more.
- Transfer the filling to a resealable plastic bag, push to a bottom corner, and cut a roughly 1/2-inch opening off that corner.
- When the cookies are completely cool, turn half of them over on their tops and pipe the filling (about 1 rounded teaspoon) on each cookie bottom. Close with the cookie tops and gently flatten. Store in an airtight container at room temperature for up to 3 days.