Gianduja Chocolate Squares

For Praline Paste: Spread hazelnuts in a baking pan and toast in a 325 degrees F oven until browned, about 8 minutes. Wrap nuts in a kitchen towel and rub briskly to remove the skins.

Place nuts in a food processor and pulse until very finely ground. Add the vegetable oil and process until the mixture forms a thick paste, similar to peanut butter (Praline can be made ahead to this point, tightly sealed and refrigerated for several months. Bring to room temperature before using).

Line an 8-inch square baking pan with waxed paper so it extends over the sides.

In a double boiler or in a metal bowl set over simmering water, melt bittersweet and milk chocolates over low heat, stirring often with a rubber spatula. Remove from heat and stir in the praline paste until well blended. Pour the mixture into the lined pan and cover tightly with plastic wrap.

Refrigerate until firm, about 2 hours. Remove from refrigerator, lift out the wax paper and gently peel off. Dip a sharp knife into hot water and dry it, then cut the chocolate into 2-inch squares.

Place each square in a paper candy cup. Store squares between sheets of waxed paper in tightly sealed container. Store in refrigerator up to 3 weeks. Bring to room temperature before serving.