Beat the butter until soft, then add the sugar and beat until light and fluffy. Stir in vanilla, eggs, then molasses until well-blended.

Whisk together flour, baking soda, salt, cinnamon, ginger, and pepper in a separate bowl.

Gradually add dry ingredients to the wet mixture in thirds, mixing just until incorporated. Press the dough firmly into a 9×5‑inch loaf pan lined with plastic wrap, smoothing the top.

Freeze the dough until very firm, preferably overnight.

Preheat oven to 350 °F (175 °C). Remove dough from pan and slice into very thin pieces (no more than 1/8″ thick).

Place slices on parchment or silicone‑lined baking sheets at least 1″ apart. Bake for 7–12 minutes, until edges darken slightly. Check at around 7 minutes for crispness.

Let cool on the baking sheet briefly, then transfer to a wire rack to cool completely.