Preheat oven to 325℉. Line cookie sheet with parchment paper.
In a large mixing bowl or stand mixer fitted with the whisk attachment add butter, shortening, vanilla, sugar and brown sugar and cream on medium speed for 3 minutes.
½ cup unsalted butter, ½ cup butter flavored shortening, 1 teaspoon vanilla extract, ¾ cup white granulated sugar, ¾ cup light brown sugar
Add eggs and mix on low speed until just incorporated.
2 large eggs
In a small mixing bowl, whisk together flour, baking soda, baking powder, cornstarch and salt. Using the beater attachment on low speed or a spatula by hand, gradually blend dry mixture into wet mixture until well combined. Fold in miniature chocolate chips, reserving some to top cookies.
2½ cups all purpose flour, 2 teaspoons baking soda, ½ teaspoon baking powder, ½ teaspoon corn starch, 1 teaspoon salt, 1¼ cups miniature chocolate chips
Coat a 1 teaspoon measuring spoon with non-stick spray. Scoop dough and divide in half, coating with spray every 5 scoops. Roll into balls and drop 12 spaced evenly onto a half cookie sheet or 24 onto a full sized cookie sheet. Gently press chocolate onto the top of each cookie.
Bake in the center of a pre-heated oven 6-8 minutes, until the edges are slightly golden brown and the cookie appears to be set.Allow to cool 1 minute. Using a cookie spatular, transfer to a wire cooling rack until they reach room temperature.
Notes
Do not overbake. Remove from the oven when the edges are just set and allow to cool on a wire rack for best results.