MAKE THE Filling
In a medium bowl, whisk the brown sugar with the cornstarch, salt and 1/2 cup of the half-and-half. Strain the half-and-half mixture through a fine sieve into a medium saucepan using a rubber spatula to press out any lumps of sugar. Whisk in the remaining 1 cup of half-and-half and the egg yolks. Cook the half-and-half mixture over moderate heat, stirring constantly with a heatproof rubber spatula, until it is thick and bubbling, about 7 minutes. Off the heat, whisk in the butter and the vanilla. Scrape the butterscotch pudding into a bowl and press a piece of plastic wrap directly onto the surface. Refrigerate the butterscotch pudding until chilled, at least 3 hours or overnight.