Frozen Matcha Gateau

Name: Frozen Matcha Gateau
Ingredients: Crust:; 150 g Amaretti Biscuits / Any Store-Bought Gluten-Free Biscuits or Cookies,; Unsalted Butter Melted, 30g + More For Greasing; 1 TBSP Demerara Sugar,; Custard:; 100 g Whole Milk,; 25 g Heavy Whipping Cream.; 1 Egg Yolk,; 22 g Demerara Sugar,; 10 g Cornflour,; Gateau:; 350 g Heavy Whipping Cream,; Pinch Sea Salt,; Nature's Superfoods' Organic Matcha Powder, 15g Adjust To Preference; 300 g High Quality White Chocolate Preferably Valrhona,; 2 TBSP Yuzu Sake,; Coating:; 200 g High Quality White Chocolate Preferably Valrhona,; 80 g Canola / Peanut / Grapeseed Oil,; Nature's Superfoods' Organic Matcha Powder, For Dusting