Unsalted butter and all purpose flour for baking pan
2 1/2 c. all purpose flour
1 tsp. baking soda
1 tsp. cream of tartar
1/4 tsp. ground mace
1/4 tsp. ground cinnamon
1/4 tsp. freshly grated nutmeg
3/4 c. unsalted butter, softened
1 c. (packed) dark brown sugar
1/2 c. milk
1 c. moist raisins, coarsely chopped
1 tsp. grated lemon zest

Heat oven to 375 degrees. Generously butter and flour 15 1/4 x 10 1/2 inch jelly roll pan. Sift together flour, baking soda, cream of tartar, mace, cinnamon and nutmeg in a bowl. Beat butter and sugar in large bowl until light. Beat in eggs until just blended. Stir in flour mixture in 3 additions and milk in two, beginning and ending with flour; stir in raisins and lemon zest. Spoon into prepared pan; smooth top with spatula. Bake until top of cake is lightly browned and edges pull away from sides of pan, 15 to 20 minutes. Remove to wire rack and cool, cover tightly with foil and let mellow at room temperature 1 to 3 days. Cut into 2 inch squares to serve.