For the Pretzel Whip, bring all ingredients to a simmer. Remove from heat, cover, and let steep for at least 30 minutes. Strain and chill.
For the brittle, warm peanut butter over double boiler. In another saucepot, cook sugar, glucose, water and butter until light amber in color. Add baking soda and vanilla to the pot and stir in the warmed peanut butter. Mix until just combined and pour onto silpat right away. When cool, break up the brittle into bite-size pieces.