Melt the butter in the microwave using 50% power. Let cool completely, then put in the mixing bowl.
In a mixing bowl, combine the melted butter, date syrup, brown sugar and granulated sugar. Stir well, then stir in the egg and vanilla extract.
Combine the flour, baking powder, baking soda and salt. Add to the date syrup mixture and stir until blended, then stir in the chocolate chips (and walnuts, if using).
Using a (generously scooped!) medium cookie scoop or a heaping tablespoon, drop mounds of dough onto a plate lined with plastic wrap. Cover and chill the mounds for 1 hour or until ready to bake. Chilling overnight makes the cookies even better.
Bake for 12 to 15 minutes at 350 degrees F. Let cool on the baking sheet for 5 minutes, then transfer to a wire rack to finish cooling. And here's the difficult part. Let the cookies cool completely. For some reason, these are better once they've cooled and set.
Note: It’s important to weigh the flour to get 220 grams. If you don’t have a scale, stir the flour and spoon it into the cup.