Checkerboard Sablés

• 7 oz sugar
• 11 ½ oz all-purpose flour
• 4 ½ oz unsalted butter, diced, chilled
• 1 large egg
• ½ tsp pure vanilla extract (optional)
• ¼ tsp salt

Chocolate Dough

• 11 ½ oz all-purpose flour
• 4 ½ oz unsalted butter, diced, chilled
• 1 large egg
• 1 oz unsweetened cocoa powder
• ½ tsp pure vanilla extract (optional)
• ¼ tsp salt