1. Preheat oven to 350 F. Line a baking sheet with parchment.
2. Melt butter in a small saucepan.
3. Pour butter into a large bowl and allow to cool a few minutes. Add sugars and stir until well combined.
4. Add eggs, one at a time, stirring to incorporate. Mix in vanilla.
5. In a small bowl, mix together dry ingredients. Pour dry ingredients into melted butter mixture. Stir just until barely combined.
6. Add chocolate and pistachios and fold in gently.
7. Scoop out dough balls (about 2 Tbsp) using a spoon or ice cream scoop. Place about 1" apart on prepared baking sheet.
8. Bake until golden brown around edges, 10-11 minutes for small cookies or about 13 minutes for slightly larger cookies.
9. Sprinkle with Maldon flakes toward the end of bake time or right when cookies come out of oven.
Enjoy warm with milk or coffee!
Cookies will keep well in an airtight container at room temperature for 5-7 days.