Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a large mixing bowl, cream together 1 cup softened unsalted butter, 1 cup granulated sugar, and 1 cup packed light brown sugar until light and fluffy, about 3-4 minutes.
Beat in 2 large eggs one at a time, then stir in 2 teaspoons vanilla extract until fully combined.
In a separate bowl, whisk together 3 cups all-purpose flour, 1 teaspoon baking soda, 1/2 teaspoon baking powder, and 1/2 teaspoon salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Divide the dough evenly into two bowls.
For the chocolate chip cookies: Fold 1 1/2 cups semisweet chocolate chips into one half of the dough.
Scoop tablespoon-sized portions of the chocolate chip cookie dough onto one prepared baking sheet, spacing them about 2 inches apart.
For the sugar cookies: In the second bowl with the remaining dough, mix in 1 teaspoon vanilla extract.
In a small bowl, whisk 1 large egg white until frothy. Brush the tops of the sugar cookie dough balls with the egg white, then sprinkle each with granulated sugar (use the 1/2 cup reserved for sugar cookies).
Scoop tablespoon-sized portions of the sugar cookie dough onto the second prepared baking sheet, spacing them about 2 inches apart.
Bake both cookie sheets in the preheated oven for 10-12 minutes, or until the edges are golden brown but the centers remain soft.
Remove from the oven and allow cookies to cool on the baking sheets for 5 minutes before transferring to wire racks to cool completely.