Mix together oats, coconut, flour, salt, and sugar. Set aside.
Place butter and maple syrup in a small saucepan set over medium heat. Cook and stir until melted. Remove from heat. Stir together baking soda and boiling water and add it to the melted butter along with the maple extract. Stir the butter mixture into the oats. Fold in walnuts.
Divide dough into 12 equal pieces (about 3 tablespoons each), place them about 3 inches apart on parchment lined cookie sheets, 6 to a sheet. Flatten each ball slightly with the palm of your hand.
Bake at 300ºF for 15-20 minutes or until golden brown and set. Transfer to wire racks or paper towel, to cool. Store in an airtight container, at room temperature, for up to 1 week.
Makes: 12 jumbo cookies
Adapted from Martha Stewart.