Step 1

Using half of the chopped almonds, form an 8-inch (20-cm) circle in an even layer on an ungreased baking sheet.

Step 2

Fit a small, heavy-duty saucepan with a candy thermometer, then add the water, butter, granulated sugar, and brown sugar, mixing them together. Have the baking soda and vanilla measured and ready.

Step 3

Cook the mixture over medium heat, stirring as little as possible. When the mixture reaches 300°F (150°C), remove the pan from the heat and immediately stir in the baking soda and vanilla. Mix just until combined; don’t overstir.

Step 4

Right away, pour the hot toffee mixture over the circle of almonds on the baking sheet. Using as little movement as possible, spread the toffee to cover the circle.

Step 5

Scatter the chocolate pieces over the toffee and wait 2 minutes to allow them to melt. Use a spatula to spread the chocolate into an even layer, then scatter the remaining chopped almonds on top, pressing them into the chocolate. Cool completely, until the chocolate is firm. Depending on the temperature of your kitchen, you may need to cool it in the refrigerator. Remove it once the chocolate has hardened.

Step 6

Chop the Buttercrunch Toffee into coarse chunks, then fold the pieces into 1 quart (1 liter) of ice cream as you remove it from the machine.

Step 7

Feel free to substitute toasted hazelnuts or pecans for the almonds. I also like to fleck a few grains of coarse salt over the chocolate before adding the nuts. You can substitute milk chocolate for the dark chocolate if you wish.

Step 8

Buttercrunch Toffee can be stored in an airtight container for up to 2 weeks in the freezer or at room temperature.