Preheat oven to 350 and line or spray pans with baking paper.

Two ways to partially melt better. Place in microwave and partially melt halfway (do not melt completely) or use metal bowl, place butter inside bowl and in preheating oven. Leave just a few minutes, until butter starts to melt around outside (approx half butter melted). Take out of oven to cool.

When butter has cooled, add sugars and beat with mixer until fluffy. Add vanilla and eggs, beating between each addition just until mixed. Add flour, baking soda, salt and beat on low, just until combined.  If dough is wet, add 1-3 spoonfuls until dough comes together in a ball and does not stick to bowl.  Fold in chocolate chips.  

Use cookie scoop (1/4 cup large, 1.5 Tbsp medium) and drop dough onto baking sheets, allowing room for spreading. Pat down cookies a little and press additional chocolate chips on top.

Bake one tray of cookies at a time, 10-12 minutes for large, 8-9 for small. Don't over-bake. Cool on wire rack. Makes 1 dozen large or 2 dozen small cookies. Store cookies in air-tight container.