Soft Mustard Molasses Cookies

adapted from Gourmet Magazine

• 1 3/4 cups all-purpose flour
• 1 1/2 teaspoons cinnamon
• 1 1/2 teaspoons ground ginger
• 1/2 teaspoon cream of tartar
• 1/2 teaspoon baking soda
• 1/4 teaspoon salt
• 1 stick unsalted butter, softened
• 1/2 cup packed dark brown sugar
• 1 large egg at room temperature 30 minutes
• 1 1/2 tablespoons Dijon mustard
• 1/3 cup mild molasses
• 1/3 cup sour cream
• Demerara sugar for sprinkling (optional)

Preheat oven to 350°F with rack in middle. Grease 2 large baking sheets.

Whisk together flour, cinnamon, ginger, cream of tartar, baking soda, and salt.

Beat butter and brown sugar with an electric mixer at medium speed until pale and fluffy, then beat in egg, mustard, and molasses (mixture may look curdled).

At low speed, mix in flour mixture in 3 batches, alternating with sour cream, beginning and ending with flour mixture, and mixing just until smooth.

Drop 1 1/2 Tbsp batter per cookie onto baking sheets, arranging them 3 inches apart (cookies will spread). Sprinkle with Demerara sugar.

Bake, 1 sheet at a time, until cookies are puffed and dry to the touch, 17 to 19 minutes. Cool on sheet 1 minute, then transfer cookies to a rack to cool.