Preheat oven to 350F (177C) and line two metal 13x9 pan with parchment paper (if you don't have two 13x9 pans, you can use one 13x9 and one cookie sheet, which is what I usually do).
In KitchenAid stand mixer or using an electric mixer, beat the softened butter until creamy.
Add condensed milk and sugar and beat well.
Scrape down the sides and add vanilla extract and beat on low.
Gradually add in flour and salt until combined. Scrape down the sides of the bowl as needed.
Stir in chocolate chips.
Spread half of the batter into prepared 13x9 pan (this can be tricky, especially with the slippery parchment paper. I use the back end of a spoon to press it into the pan and then lay a sheet of wax paper over the top and use my hands over the wax paper to press the batter evenly into the pan) and the remaining half into your other prepared pan (or spread evenly (about ¼" thick) over parchment paper-lined cookie sheet).
Bake (one pan at a time) on 350F (177C) for 20-25 minutes (until edges are golden brown).
Cool for five minutes and then use a sharp knife or pizza cutter to cut shapes into the brittle (I just slice it into triangle shaped place). Do not try to separate the pieces, just score the marks and then allow the cookie brittle to cool completely.
Once cookie brittle has cooled, break apart pieces on the scored lines.
Prepare melting wafers according to package instructions and use a spoon to drizzle melted chocolate over the surface of the cookie brittle. Allow chocolate to harden before enjoying.