A Dairy Queen Blizzard is different from other ice cream, not only because of the optional mix-ins, such as crumbled candy bars and cookie-dough chunks -- but for its texture and lift. The Blizzard base -- vanilla-flavored soft-serve -- gets its texture and structure from natural food additives such as corn syrup and corn starch. Making a homemade Blizzard is easy, but deciding the ingredients to mix into it might take some time.
Add 3 cups of half-and-half to a saucepan to make 1 quart of Blizzard. Sweeten the half-and-half with sugar and add vanilla extract to taste.
Whisk 1/4 cup each of corn starch and half-and-half in a bowl until smooth. In a second bowl, add 2 tablespoons of half-and-half and sprinkle 2 teaspoons of gelatin over it.
Bring the saucepan of half-and-half to a simmer and whisk in the cornstarch slurry. Simmer the half-and-half until thickened, about 5 minutes. Take the saucepan off the stove.
Taste the half-and-half and adjust the taste as needed with sugar and vanilla. Pour the gelatin-and-half-and-half mixture into the saucepan and whisk it until combined.
Transfer the Blizzard base to an airtight container and chill it in the refrigerator until the gelatin sets, about 4 hours.
Churn the soft-serve in a crank-style ice-cream maker or electric maker until it has a creamy, semi-soft texture. Stir in the candy pieces of choice. Store the blizzard in an airtight container in the freezer; let it sit at room temperature for 10 minutes to regain the soft-serve texture.