Preheat oven to 325 degrees F. Mix flour, baking soda and salt and set aside.
In a large bowl, add cooled, melted butter and whisk sugar into it until smooth. Add in egg and egg yolk, mixing to combine, then whisk in vanilla and lemon extracts, lemon juice and lemon zest. Stir in dry ingredients, mixing until a dough forms. If needed, use your hands to create the dough (I did).
Using an ice cream spoon, scoop the dough into golf-ball sized balls and place on a baking sheet 2 inches apart. Bake for 10-12 minutes, or until middle is just set an edges are slightly golden.
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