• In a large bowl or the bowl of a stand mixer, beat the butter with a mixer for 1 minute at medium-high speed.
• Add the sugar and beat for another 2 minutes, until creamy and fluffy.
• Add the whole egg and mix to combine. Scrape the bowl and mix briefly.
• Add the egg yolk and the vanilla, and mix until incorporated.
• Add the flour, baking powder, baking soda, and salt to the bowl.
• Mix on low until the ingredients come together.
• Add the frozen blueberries and the white chocolate chips. Mix just until incorporated so the blueberries don’t come undone. It’s important the blueberries are frozen when you add them.
• Scoop the cookies into small balls using a cookie scoop, and place each cookie in a tray lined with parchment paper.
• Place the cookies in the freezer while you pre-heat the oven to 350ºF, for about 15 minutes.
• Once the oven is pre-heated, place the cookie balls on a tray lined with parchment paper or a silicone mat, at least 2 inches apart from each other.
• Bake the cookies in the oven for 10 to 12 minutes, until they are set on the outside and slightly golden.
• Store the cookies at room temperature in an airtight container for up to 3 to 4 days.

Blueberry Glaze

• Place the blueberries in a small bowl, use a food processor to blend them. You can add a tsp of water or milk to make more liquid.
• Strain the blueberry juice and add 1 to 2 tbsp of it to the powdered sugar and whisk until smooth. If needed, add bit more milk or water to achieve the desired consistency. Drizzle over the cooled cookies. If you let the cookies rest for about 30 minutes, the glaze should crust and won't be wet or sticky.