In a large mixing bowl, whisk together flour, baking soda, ground ginger, ground cinnamon, ground nutmeg, ground cloves, and fine sea salt until combined.

Cream butter with brown sugar until light and fluffy. Add egg and molasses, mixing until smooth. Gradually incorporate the flour mixture until cohesive.

Scoop cookie dough into 1.5-tablespoon balls, place on parchment-lined baking sheet, cover with plastic wrap, and refrigerate for at least 3 hours.

Preheat oven to 350°F (180°C). Roll chilled dough balls in granulated sugar and create thumbprints with a spoon.

Bake for 9-10 minutes until soft and slightly puffed. Cool before moving to a wire rack.

Melt white chocolate and eggnog in a microwave-safe bowl, stirring until smooth. Fill thumbprints with this mixture.

Allow cookies to set at room temperature.