Birthday- cake & champagne! Playa Negra or Tamarindo

I am going to be staying in Playa Negra, and looking to celebrate my partner's 50th birthday I believe we are going to do the Antares sailing tour in the afternoon, and I want to surprise him with a cake and champagne either on the boat or at a restaurant afterwards. I've reached out to the boat to ask if they can provide it, no answer yet. Is there a beachfront restaurant that would do a special birthday celebration in Tamarindo? There's supposed to be a nice place where we are staying in Playa Negra. I could also try to pick up a cake and bring it back with us.

So- I'm looking for recommendations in either Tamarindo for a bakery that will make a cake to order or a restaurant with good ambiance that will do a special birthday celebration. And some champagne- is that easy to find/buy or should I put a bottle in a checked bag and bring it with me?