Preheat the oven to 350°F. Spray a 13x9x2-inch baking pan with nonstick spray.
PREPARE THE BROWNIES:
In a large bowl, use an electric mixer to combine the butter, eggs and vanilla. In a separate bowl, whisk together the dry ingredients; add to the butter mixture and mix well. Stir in the water, chocolate chips and toffee chips until combined. Pour into the prepared pan and spread evenly.
Bake 30 to 35 minutes or until the brownies begin to pull away from the sides of the pan. Cool on a wire rack.
PREPARE THE GLAZE:
In a saucepan, combine the chips, milk and butter over medium heat (stirring) until the chips and butter are melted and smooth. Remove from the heat; whisk in the powdered sugar and vanilla until smooth. Spread the glaze over the brownies. Let the brownies cool completely (the refrigerator works well for this), then cut into bars. They will be fudgy, so use a thin metal spatula to get them out of the pan.