You will only need two ingredients to cook clear isomalt: isomalt and water.
For every cup of isomalt you cook, the water volume will be approximately 1/8 of that amount of isomalt (ex. 1/8 cup of water for every 1 cup of isomalt).
Place the isomalt in a small pot over medium heat
Allow the isomalt crystals to melt without stirring them
Once the isomalt is boiling, remove the isomalt from heat. Isomalt will be very bubbly.
Hold the small pot off of the heat until the bubbles settle down.
Once the bubbles have settled down, place the pot back down on the burner and stir in the water, a little at a time. Steam will aggressively come off of the sugar as the water is now cooling it down. Isomalt will still be very bubbly.
Reduce the amount of air bubbles in the hot isomalt by placing it in the oven at 265F for 10 minutes. If you skip this step, the bubbles will stay in the isomalt and will harden like the cookies on the left in the above picture.
After 10 minutes, carefully remove pot of isomalt from oven and use the isomalt while it is still hot. If the isomalt starts to thicken, place it back in the oven for 2 - 3 minutes until it liquefies again
How do I make these cookies with isomalt?
You will need your favourite sugar cookie or shortbread cookie recipe (i.e., a cookie that does not spread much in the oven), liquid isomalt, royal icing, and your favourite sprinkles.
Follow your recipe's instructions to prepare the cookie dough. After you have rolled out your cookies and cut them into the desired shape and then cut a hole where you want the isomalt to fill. Bake the cookies according to recipe.
Allow the cookies to cool on the baking sheet as you prepare the isomalt according to instructions above.
Once the isomalt is ready to be used, carefully pour the isomalt into the hole of the baked cookie. Allow the isomalt to cool undisturbed for at least 20 minutes, until it has completely set.
Once the isomalt has set, place one isomalt-filled cookie down. Apply royal icing to the edges of the cookie, being cautious to not get any icing on the 'glass.' Stack the hollow cookie before the royal icing dries. Fill your cookie with sprinkles of choice. Attach last isomalt-filled cookie with royal icing to 'seal' the cookie.
Shake, shake, shake!
Notes
To make one sprinkle-filled cookie, you will need 3 cookie cut-outs. Two of the cookie cut-outs will be filled with isomalt. These two filled cookies will be on the outside your assembled stacked cookie. The order you stack them should be: isomalt-filled cookie, hollow cookie, isomalt-filled cookie. The purpose of the hollow cookie in the centre is to add extra height to the stacked cookie, which then allow the sprinkles to move freely.