Preheat oven to 350. Line baking dish (either 8x8 or 9x9) with parchment paper allowing paper to extend out over edge. This will make it easy to pull cookie out of baking dish and no mess.

IN a small pot melt butter over med-high heat. Allow butter to slowly foam up and turn brown. This takes a little time so be patient. Give it a stir every once in awhile. Once it's turned brown and smells nutty you can remove from heat.

Add butter to bowl with brown sugar. Mix well. Whisk in egg and vanilla. In a separate bowl or measuring cup add flour, baking soda and salt. Mix and pour into brown sugar mixture. Stir. Pour in your additions. For these I used peanut butter chips & chocolate chips. Stir again and pour batter into parchment lined dish. You will need to spread it out with a spatula ensuring evenness in all four corners.

Bake about 20-25 minutes or until toothpick comes out clean. Remove entire cookie bar, cut and eat warm or let cool on wire rack, cut into squares and keep in container until ready to serve. Equally divine with a big scoop of ice cream on top.