Your recipe boutique page is missing your View Cart code, which is required to display the overlay-style cart "inside" your page. Whenever the overlay cart cannot be displayed, the cart buttons on that page will still work in "fallback mode" by opening a separate window/tab to display the cart there; however, because of the way browsers handle cookies, items added to the fallback cart cannot appear in the overlay cart and vice-versa.
Just copy your View Cart code from Seller Admin and paste that into your recipe boutique page -- better yet, see if you can paste your View Cart code into a common header, footer, or sidebar area that gets added to every page on your site automatically.