To make the “granola glue” or peanut butter sauce, combine honey and brown sugar in a small saucepan. Heat, while stirring, until the brown sugar dissolves. Bring mixture to a simmer and simmer for 1-2 minutes until evenly foamy/bubbly on top. Remove from the heat. Add one teaspoon vanilla extract. Stir (it will steam a bit). Add peanut butter and stir briskly until lumps are gone and the consistency is uniform.
Pour granola glue in bowl with dry ingredients and mix.
Place the mixture in pan and press down with a fork to smooth out.
Place in fridge for at least an hour (I leave it in overnight).