Warm the butter over hot water to melt. Peel the kabocha and boil. Preheat oven at 180°C/360°F. Grease the pan with oil (not listed).
Blend the biscuit and butter in a food processor and press the dough along the pan. Chill in the fridge after it's evenly spread out.
Drain the boiled kabocha. Combine with sugar, beaten eggs, heavy cream, and vanilla oil. Mix well.
Pour the kabocha mixture from Step 3 into the pan from Step 2. Bake in the oven for 25-30 minutes. Cool on a rack, then remove the pan carefully.
Draw eyes and mouth on parchment paper and carve them out to make a paper stencil. Use a tea strainer to dust cocoa powder (not listed) through the stencil to make the face.
It's easier to remove the cake pan if you use a springform pan.
Story Behind this Recipe
I start craving these tarts whenever it's Halloween. It's immediately sold out when I sell them at bake sales.
If you don't own a food processor, you can use two layers of plastic bags. Put the biscuits inside and pound with a rolling pin. The measurements in brackets are only if you are using a tart pan. The ingredients without any bracketed measurements means you use the same amount for both pans.