Preheat the oven to 350˚F. Line a sheet pan with parchment paper or a silicone baking mat.
Stir together flour, brown sugar, baking powder, baking soda, kosher salt in a mixing bowl.
Stir together maple syrup and oil with a fork in a separate bowl or measuring cup.
Add wet mixture to dry mixture and stir to combine.
Fold in chocolate chunks, walnuts and cranberries.
Scoop into 12 even balls spaced evenly on a sheet pan. Dip fingertips into water and flatten each cookie dough ball slightly. Then sprinkle flaky sea salt over each cookie.
Freeze cookies on a sheet pan for 10 minutes. Then remove from freezer and bake at 350˚F for about 12-15 minutes until edges are golden brown, but centers are still soft.
Transfer cookies to a cooling rack with a spatula and cool to room temperature. Then store them in an airtight container for up to 1 week.