1. Preheat the oven to 250 degrees F. Line 2 baking sheets with silicone liners or parchment paper.
2. In the clean bowl of a stand mixer (you could also use a hand-held mixer), beat the egg whites on medium-high until they begin to foam. Add in the cream of tartar and salt and continue to beat until the whites become light and fluffy, 3 to 4 minutes.
3. With the machine on medium speed, gradually add in the sugar and extract. Turn the machine to medium-high again and beat until the whites become nice and glossy, 7 to 10 minutes.
4. Gently fold in the chocolate covered toffee pieces. Using 2 teaspoons, dollop the meringue (in about 1 1/2-inch balls) onto the prepared baking sheet an inch apart from each other.
5. Place the meringue in the oven to bake for 2 hours. Once the meringue cookies are dry to the touch, turn off the oven, leave the door ajar and let them sit in there for another hour.
6. Remove the cookies and enjoy at once, or store in an airtight container and eat them later.