Preheat the oven to 350°F (175°C).
Coarsely chop the pecans, spread them on a baking sheet and bake until lightly toasted and fragrant, 8 to 10 minutes. Let cool and set aside.
Cut the crystallized ginger into very small pieces. Set aside.
In a bowl, mix the flour, baking soda, ground ginger, cinnamon, salt and pepper.
In another bowl, beat the butter and sugar with an electric mixer until creamy, about 5 minutes.
Add the egg and beat for another 5 minutes.
Add the molasses and keep beating until the mixture is smooth.
Add the flour mixture and beat until well combined, 2 to 3 minutes.
Fold in the crystallized ginger and pecans.
On a floured surface, divide the dough into two equal portions and shape into logs 1 ½ inches (4 cm) in diameter. Wrap the logs in plastic wrap and refrigerate for at least 4 hours.
Preheat the oven to 325°F (165°C). Line two baking sheets with parchment paper or a silicone mat.
With a sharp straight-edge knife, cut each log into ⅛-inch (0.3 cm) slices. Place them on the baking sheets, leaving 1 inch (2.5 cm) between them.
Bake until golden, 8 to 10 minutes.
Remove from the oven and let cool completely on a wire rack.