Whisk the flour, cornstarch, baking soda and salt in a medium bowl. Set aside.
Beat the melted butter, brown sugar, granulated sugar and vanilla and almond extracts in a large bowl with a mixer on medium speed until thick and creamy, about 2 minutes. Beat in the egg and egg yolk. Reduce the mixer speed to low and beat in the flour mixture until just combined. Stir in 1 cup each chocolate chips and shredded coconut. Refrigerate the dough until firm enough to scoop, about 1 hour.
Position racks in the upper and lower thirds of the oven; preheat to 350 degrees F. Line 2 baking sheets with parchment paper. Arrange tablespoon-size scoops of dough about 2 inches apart on the baking sheets. Bake, switching the pans halfway through, until lightly golden, 12 to 14 minutes. Let cool completely on the baking sheets.
Put the remaining 1 1/2 cups shredded coconut in a medium bowl. Melt the remaining 2 cups chocolate chips with the vegetable oil in a small saucepan over low heat, stirring, until smooth. Dip each cookie partway in the melted chocolate, then immediately dip in the coconut. Return to the parchment-lined baking sheets and refrigerate until set, about 30 minutes.