Prep the pan: Heat oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment, leaving overhang for easy lifting. Lightly grease the parchment.

Cream the butter and sugars: In a large bowl, beat 1 cup softened butter with 3/4 cup brown sugar and 1/2 cup granulated sugar until light and fluffy, about 2–3 minutes.

Add wet ingredients: Beat in 2 large eggs, then 1/2 cup molasses and 2 teaspoons vanilla. Scrape the bowl. The mixture may look slightly separated—this is normal.

Whisk dry ingredients: In a separate bowl, whisk 3 cups all-purpose flour, 1 teaspoon baking soda, 1/2 teaspoon salt, 2 teaspoons ground ginger, 1 1/2 teaspoons cinnamon, 1/4 teaspoon cloves, and 1/4 teaspoon nutmeg.

Combine: Add the dry ingredients to the wet in two additions, mixing on low just until combined. Do not overmix. The dough will be thick and sticky.

Spread and bake: Press the dough into the prepared pan in an even layer. A spatula or damp fingertips help. Bake for 18–22 minutes, until the center is set and a toothpick comes out with a few moist crumbs. Do not overbake.

Cool completely: Place the pan on a rack and let the bars cool in the pan. Lifting warm bars can cause cracking.

Make the frosting: Beat 8 ounces softened cream cheese with 1/2 cup softened butter until smooth. Add 2 teaspoons vanilla and 2–3 cups powdered sugar, beating until fluffy. Add 1–2 tablespoons milk to reach a spreadable consistency. For a bright twist, mix in 1 teaspoon orange zest.

Frost: Lift the cooled slab from the pan using the parchment. Spread frosting evenly. Add sprinkles or crushed peppermint if using.

Slice and serve: For clean cuts, chill for 15–20 minutes before slicing into 16–20 bars. Wipe the knife between cuts.