In the bowl of a stand mixer (or in a large bowl with a hand mixer), cream together butter and sugar until light and fluffy, 2-3 minutes.
Add egg, pumpkin purée and molasses and mix until combined.
In a separate large bowl, whisk together flour, baking soda, ginger, cinnamon, ground cloves, and salt.
Pour flour mixture into wet mixture and mix until just combined, taking care not to over-mix. Fold in toffee pieces.
Place dough in refrigerator for at least 20 minutes.
Pre-heat oven to 350 degrees and line a baking sheet with parchment paper.
Scoop tablespoons of dough, roll in extra sugar until well coated, and place on prepared- baking sheets about 1 inch apart.
Bake for about 7-10 minutes, until cookies are just starting to brown at edges.
Let cool in pan for a 5-10 minutes before moving to rack to cool completely.