1Heat oven to 350°F. Grease and flour 12-cup fluted tube cake pan.
2Beat Bisquick, granulated sugar, brown sugar, butter, pumpkin pie spice, 1/4 cup milk, eggs and pumpkin in large bowl on low speed 30 seconds. Beat on medium speed 3 minutes. Spread in pan.
3Bake about 50 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes; turn upside down onto heatproof plate or wire cooling rack. Remove pan; cool cake completely.
4Stir remaining ingredients until smooth and thin enough to drizzle. Drizzle over cake.