Preheat oven to 350°F. Line a baking sheet with parchment paper or a silicone baking mat; set aside.
In a medium bowl, whisk together 2 cups all-purpose flour, 1 teaspoon baking soda, 1 (3.5 oz) pkg instant pudding mix OR 1 tablespoon cornstarch (vanilla or lemon), and 1/4 teaspoon salt. Set aside.
In a large bowl, whisk 1/2 cup (1 stick) melted unsalted butter with 3/4 cup packed brown sugar and 1/4 cup granulated sugar until well combined, about 1 minute. If the butter is very hot, let it cool briefly so it won't cook the egg.
Add 1/2 teaspoon pure vanilla extract and the zest of 1 lemon to the butter-sugar mixture and whisk to combine.
Add 1 large egg and whisk until fully incorporated.
Add the dry ingredients to the wet mixture and then add 1/2 cup of the 1 1/4 cups white chocolate chips. Stir with a spatula or wooden spoon until just combined (do not overmix).
Using a 1½-tablespoon cookie scoop, portion the dough and roll each portion into a ball. Place the dough balls about 2 inches apart on the prepared baking sheet.
Press 5 to 6 white chocolate chips onto the top and sides of each cookie using the remaining white chocolate chips (reserve about 3/4 cup).
Bake cookies for 10 to 11 minutes, until the edges are set and the centers are still slightly soft.
Cool the cookies on the baking sheet for 5 minutes, then transfer them to a wire cooling rack to cool completely.