Place butter in the bowl of a stand mixer (or you may use a large bowl and an electric mixer, but the mint dough becomes very stiff so I do recommend using an electric mixer rather than stirring by hand) and beat briefly until creamy.
Turn mixer to low-speed. Gradually add two cups (250g) of powdered sugar, stirring until combined.
Add extracts and salt and stir well, until completely combined.
Add heavy cream and stir, gradually increase mixer speed to medium.
Turn mixer to low-speed and gradually add remaining 2 cups (250g) powdered sugar until completely combined. Be sure to pause and scrape the sides and bottom of the bowl to ensure all ingredients are well-combined.
If mixture is still sticky at all, add additional powdered sugar, 1 tablespoon at a time, until no longer sticky and you’ve achieved a playdough-like consistency.
If desired, color with food coloring at this point.
Break off about 1-2 Tablespoons of mint dough and roll between your palms into a ½” thick log. Place on wax paper-lined cookie sheet and use a sharp knife to cut into pieces between ¼-½” long. Repeat until you have rolled and cut all of your dough.
Allow to sit (uncovered) at room temperature for several hours until dry and then transfer to an airtight container. Keep mints in a single layer with a sheet of wax paper between layers. Mints will keep in a cool dry place at room temperature for up to two weeks or up to a month in the refrigerator.