Preheat the oven to 375 degrees F and line baking sheets with parchment.

Place the butter, brown sugar and granulated sugar in a large mixing bowl and beat on medium-high speed until very pale and fluffy (3 to 5 minutes).

Stir in the almond butter until incorporated.

Add the egg, egg yolk, and vanilla, beating until completely incorporated.

Scrape the bottom and sides of the bowl with a silicone spatula, then add the flour, cornstarch, baking soda, and salt, stirring on medium-low speed until combined.

 Use a 1 1/2-tablespoon cookie scoop to drop balls of cookie dough onto the prepared sheets, allowing about two inches in between (for spreading).

Use the palm of your hand to press the balls slightly flat.

Bake (one sheet at a time) on the center rack of the oven for 7 to 10 minutes, or until set around the edges and just barely beginning to turn golden.

Cool completely on the baking sheet.

Dip one side of each cookie in melted chocolate, and sprinkle with a pinch of sea salt.