How do you cook an Onsen Egg in Heartopia?

You cannot use a regular stove to cook an Onsen Egg. You must visit the Onsen Baths in Onsen Mountain, interact with the small wooden baskets by the hot springs, and place 1 Pasteurised Egg inside to cook.

Where to get Pasteurised Eggs in Heartopia?

Pasteurised Eggs are sold by the NPC Massimo for 100 Gold each. He usually relocates near the Winter Utopia bus stop during the Winter Frost events. You can easily buy up to 50 eggs per day.

How to get the Onsen Egg Promise recipe?

Speak to Naughty in Onsen Mountain during the Winter Frost Season to trigger the 'Onsen Egg Promise' event. Take photos of 16 cracked eggs scattered around the region to unlock the recipe.

Database updated for March 2026

Heartopia Onsen Egg Recipe Guide: Location, Ingredients & Sell Price

The Onsen Egg is a unique consumable and highly profitable dish in Heartopia. Unlike standard recipes that you can cook in your home kitchen, the Onsen Egg is closely tied to the Winter Utopia region and requires a specific interactive cooking method. Because of its low crafting cost and high maximum sell price, it is widely considered one of the best items to cook for farming Gold.

📖 How to Unlock the Onsen Egg Recipe

The "Onsen Egg Promise" Event

During the Winter Frost Season, travel to the Onsen Mountain and speak with the NPC named Naughty. He will initiate the "Onsen Egg Promise" event.

Your objective is to find and photograph 16 unique "cracked" Onsen Eggs scattered across the snowy region. Note that these eggs appear sequentially, with only one new egg spawning per day during the event period.

Quest Rewards

Upon finding all 16 cracked eggs and completing the album, you will be rewarded with:

The Onsen Egg Recipe
Wishing Stars
Fashionwave Tokens

Note: Because this quest is tied to the Winter Frost Season event, it is currently unknown if the recipe can be bought from a bookstore or vending machine if you miss the event. We will update this guide once a permanent non-event method is discovered.

🥣 Ingredients & Cooking Location

Required Materials

The recipe is incredibly simple and requires only a single ingredient:

🥚

1x Pasteurised Egg

Cost: 100 Gold

You can purchase Pasteurised Eggs from the cooking vendor, Massimo. He sets a daily hard limit of 50 eggs per player. During the winter event, Massimo can often be found near the Winter Utopia bus stop or igloo.

Where to Cook the Onsen Egg

You cannot cook an Onsen Egg on a regular stove or kitchen appliance.

Instead, you must travel to the Onsen Baths located in Onsen Mountain. Look for the small wooden baskets resting on the edge of the hot spring water. Interact with the basket, select your Pasteurised Eggs, and place them inside the hot spring to cook the dish.

💰 Sell Price & Profit Guide

The Onsen Egg is an excellent money-maker. Since your base cost is always 100 Gold (the price of the egg), your profit depends entirely on the star rating of the cooked dish. As your Cooking Hobby level increases, you have a higher chance to yield multi-star dishes.

Star Rating	Sell Price	Net Profit
⭐ 1-Star	130 Gold	+30 Gold
⭐⭐ 2-Star	195 Gold	+95 Gold
⭐⭐⭐ 3-Star	260 Gold	+160 Gold
⭐⭐⭐⭐ 4-Star	520 Gold	+420 Gold
⭐⭐⭐⭐⭐ 5-Star	1,040 Gold	+940 Gold

💡 Tip: A high-level chef batch-cooking 50 Onsen Eggs per day can earn a massive daily passive income via 4-star and 5-star procs.