Melt the butter and let it cool until warm rather than hot. Whisk it with the granulated sugar and packed brown sugar until the mixture looks smooth.

Whisk the pumpkin purée, egg yolk, and vanilla extract into the butter and sugar mixture. Continue mixing until the wet ingredients are evenly combined.

In a separate bowl, stir together the flour, baking soda, cinnamon, ginger, nutmeg, cloves or allspice, and salt. Make sure the spices and leavening are distributed throughout the flour.

Add the dry ingredients to the pumpkin mixture and stir just until no dry flour remains. Do not overmix, since excess stirring can make the cookies less tender.

Cover the bowl and refrigerate the dough for 30–60 minutes. Chilling firms the soft, sticky pumpkin dough and helps the cookies hold their shape.

Heat the oven to 350°F (175°C) and line baking sheets with parchment paper. Scoop approximately 1 1/2 tablespoons of dough for each cookie, spacing the portions about 2 inches apart.

Bake for 10–12 minutes, until the edges are set but the centers still look slightly soft. If baking more than one sheet, rotate or switch pans only when your oven allows it without extending the bake too far.

Let the cookies cool on the baking sheet for 5–10 minutes before transferring them to a rack. They finish setting as they cool, so avoid judging doneness by fully firm centers.