Chocolate Saltine Toffee

My friend Anne passed this recipe along.

Chocolate Saltine Toffee

30 to 40 saltine crackers
2 sticks butter
1 cup brown sugar
1/2 tsp vanilla
1 1/2-2 cups chocolate chips

Line a jelly roll pan with foil and spray it very well with cooking spray. Place saltines in a single layer on the bottom of the pan. In a saucepan, combine butter and sugar, then bring to a boil while stirring constantly.  Reduce the heat and simmer, uncovered, for 3-5 minutes, stirring frequently. Remove from the heat, wait 30 seconds, add vanilla and stir. Pour mixture over the saltines. Bake at 350 for 5-7 minutes, or until toffee becomes bubbly. Let it rest for 3-5 minutes.  Sprinkle on the chocolate chips and wait for 3-5 minutes, letting them soften and melt, then spread and smooth them into an even layer with a spatula.  Break into small pieces and store in an airtight container.