Cut cold butter into chunks about one inch square. Beat in a mixer bowline high until almost smooth. Add sugars and continue beating until thoroughly combined.
Add vanilla and salt and combine.
Add flour. Beat on low until just combined.
Add chocolate chips.
Press dough evenly into a 18" X 13" X 1" half sheet pan.
Bake on the middle shelf until lightly browned, turning once or twice. This takes 30 to 45 minutes. If undercooked, the cookie brittle will not be crisp.
Cool completely. Break into chunks.
Store in an airtight container up to a week. Freezes well for up to six months.
VARIATIONS:
) Add 1 cup toasted, chopped almonds, hazelnuts, pecans or walnuts to the batter.
) Strew 1½ cups chocolate chips over the baked dough then returning to the oven for a minute or two until melted. Spread evenly then top with toasted and chopped nuts or crushed peppermint candies as a Christmas treat.
)Add finely zested orange peel and substitute one teaspoon of orange oil for the vanilla.
)Add 1 cup of chopped dried cherries to the batter.
)Use a mixture of white, milk and dark chocolate chips.
)Add one cup of toasted coconut to the batter.
NOTE: To toast nuts or coconut, spread evenly in a sheet pan and bake at 350º until lightly browned and fragrant.
Recipe by Crawfish and Caramel | Amy Eber at http://crawfishandcaramel.com/cookie-brittle/