These easy kitchen sink cookie bars are thick, soft, gooey, and chewy – a true crowd favorite! They are made in one bowl, all mixed up by hand, with no machines required!
In a medium-sized microwave-safe bowl, melt unsalted butter(¾ cup, 1 ½ sticks) for 20-30 seconds until JUST melted. (If your butter is steaming, let it cool down for a few minutes. Butter that is too hot can result in greasy bars and/or will cause the eggs to cook.)
Add in light brown sugar (¾ cup) and granulated sugar (½ cup)and use a spatula to stir until combined (* do not use a mixer!). Add in egg, extraegg yolk and vanilla extract (2 teaspoons). Mix until combined.
Stir in baking soda (1 teaspoon), baking powder (¼ teaspoon), and salt (½ teaspoon).
Add in all-purpose flour (2 cups*) and mix until all the flour disappears into the dough.
Addmix-ins of choice. I used the following: semi-sweet chocolate chips (½ cup), milk chocolate chips (½ cup), pretzel pieces (½ cup), and caramel pieces (½ cup).
Press dough into a greased or parchment-lined metal 9x13" pan until smooth. If desired, press on a few extra mix-ins to the top for aesthetics.
Bake at 350°F for 16-18 minutes until edges and top are lightly golden brown and center no longer looks wet; some ovens may need up to 20 minutes. Remove from oven and place entire pan on a cooling rack.
Allow the cookie bars to cool completely before removing from pan. Slice into 24 squares, then enjoy! To keep fresh, cover pan with saran wrap or place bars in airtight continer for up to 3 days (after that they start to dry out). See notes below for freezing tips.
Notes
*Flour: If your dough is super runny even after sitting for a few minutes, you can add an additional ¼ cup of flour. Chocolate chips: While I use a blend of semi-sweet and milk chocolate chips, you can also use dark, white chocolate, peanut butter, etc!To freeze: To freeze, cool the bars completely before placing them into an airtight container or freezer bag for storage. These will keep in freezer for 1-2 months.