You get this achievement in Chapter 2 when you are at Monty Muzzle's carnival. You need to create 6 different flavors of ice cream using the Infiniflavour machine. You then need to have Mr. Dibbins taste test each of these flavors. Dibbins is the police officer that can be found in the town all the way to the right past the newsagent stand. Here is a list of the 6 ice cream flavors you need to create:
1 - Birdseed Ice Cream: Find the birdseed in the town near the newsagent stand, then use the birdseed on the infiniflavour machine.
2 - Pie Ice Cream: Go back to Wallace and Gromit's house and in the kitchen you will find a recipe box. Use one of the recipes to bake a pie (shouldn't matter which flavor) and then use the pie on the infiniflavour machine.
3 - Bubblegum Ice Cream: When you win the gumball counting contest at the carnival, you are given a gumball as a prize, then use this on the infiniflavour machine.
4 - Fish Ice Cream: Get a goldfish by winning the "are you smarter than a chicken" game at the carnival, then use the goldfish on the infiniflavour machine.
5 - Fried Ice Cream: Use any created ice cream cone on the "will it fry" machine at the carnival and it will turn into fried ice cream.
6 - Ice cream Ice Cream: Use any created ice cream cone a second time on the infiniflavour machine. (will also get you Clone A Cone achievement)
You need to create and give each ice cream flavor to Dibbins one at a time since you are not allowed to carry more than one flavor in your inventory at a time.
After the 6th ice cream cone, Dibbins will say he is getting sick and then the achievement should unlock.