Preheat the oven to 375 degrees.: The moment you set the oven to 375 degrees , you will notice the gentle hum and gradual warmth filling the kitchen. A properly preheated oven ensures even rise and predictable browning, and if you skip this the cookies may spread too much or bake unevenly. A common mistake is placing cookies into an oven that is not fully up to temperature, which leads to pale, dense cookies; use an oven thermometer if your oven is inconsistent. You should smell a faint warmth and hear nothing dramatic, but the metal of your baking sheet will be closer to room temperature if you test it before loading. Allow the racks to settle so they are centered for even airflow. I usually set a timer and let the oven come to temperature for a full ten minutes after the indicator clicks, because ovens can plateau briefly before steadying.
In a large mixing bowl cream together the shortening and sugar. Add rest of the ingredients and mix until combined.: As you cream shortening with sugar , the mixture should lighten slightly and feel airy to the touch when you scrape a spatula across the bowl. That texture helps trap small pockets of air which give the cookie a tender lift. After creaming, add the egg , pumpkin , melted butter , and dry mix, incorporating until the batter looks uniform with streaks of spice distributed. You will notice a soft, slightly glossy batter and the scent of cinnamon and nutmeg will become more pronounced. If you overmix, the cookies may become tough, so stop once the flour is just blended in and there are no dry streaks. A common pitfall is adding hot butter right into the egg mixture which can partially cook the egg, so cool the melted butter slightly before mixing. The batter should fall slowly from the spoon in cohesive dollops rather than being runny.
Drop by teaspoon onto greased cookie sheet. Bake 10-12 minutes or until edges are golden brown. Let cool on pan 3-5 minutes. Remove to wire rack and let cool.: When you drop batter by teaspoon onto a greased sheet, the pieces should hold a soft mound shape and not flatten immediately. The visual cue to watch for is a rounded top that slightly settles, not a puddle that spreads thin. If your batter spreads too much on the sheet, chill it briefly to firm the fats, which will limit spreading. You will hear quiet, intermittent clinks as the metal pan heats in the oven moments later. For uniform cookies, scoop consistently and leave space between mounds so air can circulate; overcrowding leads to misshapen edges. Greasing is helpful, though I sometimes use parchment for cleaner release.
For the frosting cream together butter and shortening in mixing bowl. Slowly mix in the rest of the ingredients. Spread over cooled cookies.: During baking you will notice the kitchen fragrance intensify, with the top of each cookie setting and the edges turning a warm golden brown. Look for slightly firm edges and a center that still yields a touch when pressed gently; that indicates a soft interior. The first audible cue is a quiet settling sound as moisture escapes, not sizzling. After removing them from the oven, the cookies continue to cook from residual heat, which is why I let them sit on the pan for 3 to 5 minutes, allowing them to firm up enough to transfer. A frequent error is leaving cookies on the hot pan too long, which can brown the bottoms excessively, so move them to a wire rack within the recommended window. If your cookies seem underbaked, check the next batch and add a minute at a time rather than overbaking all of them.
For the frosting cream together butter and shortening in mixing bowl.: When creaming melted butter with shortening for the frosting, the texture should become silky and smooth, not curdled. Use room temperature butter that is soft but not melted, and the shortening should be slightly soft as well, which helps achieve a cohesive base for the sugar. The aroma will be rich and lightly buttery, setting the stage for the powdered sugar to bring sweetness. If the fats are too warm the frosting will be runny, and if too cold it will remain lumpy, so aim for a soft, spreadable consistency before adding sugar. A common mistake is rushing to add powdered sugar which can make the mixture dusty and harder to blend evenly.
Slowly mix in the rest of the ingredients. Spread over cooled cookies.: As you slowly blend in powdered sugar , milk , and vanilla extract , the frosting will thicken and the aroma will change to sweet and fragrant. The sound of mixing is a gentle whir rather than clatter, and the surface should look glossy and smooth without lumps. Begin with small amounts of milk, since the powdered sugar can quickly loosen the frosting; you want a spreadable, pipeable texture that will sit atop the cookie. Frosting warm cookies will cause it to melt and run, so ensure cookies are fully cooled on the wire rack . A typical issue is adding too much milk which yields a runny topping, so correct by adding more powdered sugar to thicken. When spreading, use a small offset or knife and a gentle touch to keep frosting even and avoid tearing the cookie surface.