Place the almonds and pecans in the bowl of a food processor and pulse until they are broken up into very small bits.
Add the vanilla extract and a pinch of coarse kosher salt and pulse a few more times. Add the dates and process until a thick dough forms. The mixture should stick together when pinched between your thumb and forefinger. If the dough seems too dry add water, a few drops at a time, and process until desired consistency is reached.
Dump the dough out onto a sheet of wax or parchment paper. Use the paper to form the dough into a uniformly flat square about 1 inch thick. Wrap the dough well in plastic wrap. Place in the refrigerator or the freezer for about 15 minutes before cutting into squares.
Wrap well in plastic wrap or store in an airtight container for up to a week, or the freezer for up to 3 months.