Into a large mixing bowl, add the softened butter, sugar, brown sugar, salt, and vanilla extract, and combine with an electric hand mixer for 2-3 minutes. Add the egg, egg yolk, and instant coffee, and mix until combined and creamy. Then, add the flour, and the baking soda, and mix. Fold in the chocolate chips with a spatula until the mixture is just combined. Do not overmix! Cover the bowl with plastic wrap and let the dough rest in the fridge for about 1 hour.