In a large bowl, beat lard and sugars. Mix in eggs, vanilla, and maple syrup.
Combine 3 cups flour, mint, cornstarch, baking powder, baking soda, and salt together in a separate bowl, then beat the flour mixture into the lard (or butter) mixture.
Stir in chips and chocolate chunks.
Preheat oven to 325°F.
Place teaspoonfuls of dough on cookie sheets. No need to space out much, these cookies don't spread when they bake. But you will need to flatten them with a floured cup bottom or a fork if you prefer them to be flatter instead of thick and round. The lard will hold it's shape in a thicker mound if you don't flatten them. (Both ways makes for a delicious cookie, so don't stress over this.)
Bake for 11-12 minutes, switching trays from top to bottom racks halfway through. (The cookies may appear a bit underdone, but their edges should just begin to turn golden brown.)