In a salad bowl mix 1/4 of the flour (90gr or 3.2 oz) with the butter soften at room temperature, the sugar, the egg and the salt. Once the mix is homogeneous add the rest of the flour. Mix gently. Again, once homogeneous flatten on a marble with a rolling pin. About 2 to 4 millimiters or 0.1 inch is the right thickness. Cover with a plastic sheet and let it rest and harden in the fridge for about 15 minutes. Cut it in the required shape. If you do not have a circle of the right size you may have a glass of the right diameter. Place the dough in molds. Unless you use silicone molds, you will need to butter them. Place in the oven at 160C or 320F during 15 minutes or until the crusts reach a toasted color.
While the crusts cook you have time to prepare a soft Ganache to pour inside them. Remember that the Ganache will require at least 12 hours to cristalize.