Need Suggestions for a 12-Hour Mumbai Surprise

Hey fellow Mumbaikars and travelers, A little backstory before I ask for your suggestions: My girlfriend (27F) and I (26M) are traveling from Hyderabad to Mumbai on 17th December for her birthday. It’s a surprise trip, and I’m trying to make it as special as possible because of what Mumbai means to us. Back in February, when we were still friends, we impulsively decided to explore a new city together and ended up in Mumbai for a brief 10-hour trip. That day was magical—we visited places like Siddhivinayak, Chowpatty beach, National Gallery of modern art, Marine Drive, Gateway of India, CSMT. Though we weren’t together then, this trip was the milestone which brought us together. Now, coming to the actual plan: We land at 2 PM on 17th December and fly back at 4 AM on the 18th, so it’s another short trip. Here’s what’s already planned: Lunch at Estella (Juhu) and dinner at Dome (Marine Drive). Open to suggestions for more romantic dining spots! Midnight cake cutting at the beach. I was thinking Marine Drive, but if you know of any secluded beaches nearby, let me know! Need recommendations for a great confectionery to buy her birthday cake. Since we’ve already visited the usual spots (Siddhivinayak, Marine Drive, Gateway, etc.), I’d love your ideas for unique or offbeat places to explore in this short timeframe. Something romantic, fun, or meaningful would be perfect! Thank you so much in advance for helping me make her birthday unforgettable. Let the suggestions flow—keeping in mind the time constraints (2:30 PM on 17th Dec to 3:00 AM on 18th Dec). Cheers!