1. Preheat oven to 325°.
2. Pierce pumpkin 5 times with a knife; place on a baking sheet. Bake at 325° for 1 hour and 15 minutes or until tender when pierced. Let stand 10 minutes. Discard stem, skin, and seeds. Place 1 cup chopped pumpkin (8 1/2 ounces) in a large bowl. (Save remaining pumpkin for another use.) Beat with a mixer at medium speed until smooth. Add 1/3 cup sugar and next 4 ingredients (through whole egg); beat until well blended.
3. Place half-and-half and next 4 ingredients (through milk) in a saucepan over medium heat. Heat to 180° or until tiny bubbles form around edge. Add milk mixture to pumpkin mixture. Beat at low speed 1 minute. Strain mixture through a cheesecloth-lined sieve into a bowl. Discard solids. Divide mixture evenly among 8 (4-ounce) ramekins. Place ramekins in a large roasting pan. Add hot water to pan to a depth of 1 inch; bake at 325° for 50 minutes or until center barely moves when pan is touched. Remove ramekins from pan; cool on a wire rack. Cover and chill 4 hours.
4. Combine cracker crumbs and next 4 ingredients. Spread mixture in a single layer on a baking sheet coated with cooking spray. Bake at 325° for 25 minutes. Let stand 5 minutes. Place crumb mixture in a zip-top plastic bag, and coarsely crush using a meat mallet or small heavy skillet. Top each custard with 1 table-spoon whipped topping and about 2 teaspoons graham crumble.