Melt half the dark chocolate chips in a microwave and place it in a squeeze bottle.
On some parchment paper, pipe the melted chocolate in wavy lines and use a toothpick to create the thorny appearance. You can also set something underneath to give it some texture. Place this in the fridge for a few minutes to harden up.
Mint Pastry Cream
In a pot, mix together the sugar, Corn Starch and Kosher Salt.
Mix in the Egg Yolks.
Mix in the Whole Milk and Unsalted Butter. Continuously stir over medium heat until the mixture thickens (8-10 minutes).
Remove the pastry cream from the heat. Mix in the mint extract and green food coloring.
Place a layer of plastic wrap over the pastry cream to prevent a film from forming and set aside to cool.
Optional: Pass the pastry cream through a fine mesh sieve for a smoother texture.
Preheat your oven to 350F
In a food processor, blend the Oreos, melted butter and salt until you have a sand like texture.
Press the Oreo crumbs into your mini tart pans. Use a spoon to press down, making sure it is firm.
Bake at 350F for 5-7 minutes.
After the crust has cooled and firmed up (20 minutes), melt the remaining chocolate and divide it among the four crusts. Place them in the fridge to harden up (15-20 minutes).
When the chocolate has hardened, fill the tarts with the mint pastry cream.
Pipe lines of chocolate onto the pastry cream.
Run a toothpick through the lines to create thorns.
Cover the tarts and place them in the fridge to set (at least 6 hours).
Before serving, place the other chocolate thorns on the tart.