For brownies: Preheat oven to 350°F Line a 15.5x10.5-inch jellyroll pan with foil and grease foil.
Combine butter, sugar and vanilla in a mixer bowl. Mix on low for 30 seconds then up speed and beat until creamy, about 2 minutes.
Scrape bowl down and add eggs, one at a time. Scrape bowl down again and blend in remaining brownie ingredients.
Bake for 14-16 minutes or until top springs back when lightly touched. Remove from oven and cool 2 minutes in pan. Invert onto a cutting board, remove foil and flip back over onto a wire rack; cool completely.
For butterscotch glaze: Place chips in mixer bowl. Bring water, sugar and corn syrup to a boil in a small saucepan over medium-high heat. Turn mixer on low and carefully pour in hot syrup. Mix until smooth. Cool slightly but use while still warm as mixture will set up as it cools.
For chocolate ganache: Heat cream in a small saucepan over medium-low heat until bubbles appear around the edge of the pan. Pour over chocolate chips and stir until mixture is smooth and begins to thicken. Use while warm.
To assemble brownies: Pour butterscotch glaze over brownies and spread evenly. Before glaze sets, slice brownie layer in half and stack one half on top of the other (so layers are glaze, brownie, glaze, brownie). Cool until glaze sets and drizzle top with ganache.