This is my tried and true Blue Ribbon Chocolate Chip Recipe. Make sure to melt the butter beforehand, and set eggs out about an hour so that they can reach room temperature. If possible, use Mexican vanilla, the flavor difference is incredible:
2 1/2 (1 ounce) squares unsweetened chocolate
1/2 cup butter
2 cups all-purpose flour
1/2 teaspoon baking soda
1 teaspoon baking powder
1/4 teaspoon salt
1 1/4 cups white sugar
2 eggs
1 teaspoon vanilla extract
2/3 cup sour cream
2 cups semisweet chocolate chips
Directions
1 Preheat oven to 375 degrees F (190 degrees C). In the microwave or over a double boiler, melt unsweetened chocolate and butter together, stirring occasionally until smooth. Sift together flour, baking soda, baking powder, and salt; set aside.
2 In a medium bowl, beat sugar, eggs, and vanilla until light. Mix in the chocolate mixture until well blended. Stir in the sifted ingredients alternately with sour cream, then mix in chocolate chips. Drop by rounded tablespoonfuls onto ungreased cookie sheets.
3 Bake for 8 to 10 minutes in the preheated oven. Allow cookies to cool on baking sheet for 5 minutes before transferring to a wire rack to cool completely. Store in an airtight container.