Pulse the flour, sugar, salt and baking powder in a food processor 3 or 4 times to blend. Scatter the butter over the flour and process until the mixture looks sandy and you can’t see any butter chunks.
Whisk together the egg, yolk and milk. Pour through the feed tube and pulse a few times until the dough just begins to come together (but not until the mixture forms a ball over the blade which will toughen the dough). Add some ice water drop by drop if it seems dry.
Remove the dough from the work bowl and knead it gently to form a ball. Flatten it into a disc, wrap in plastic wrap and chill in the refrigerator about 1 hour until firm but not hard. If the dough gets too cold and inflexible, leave it out for 15 minutes until it’s workable.
Lightly dust the dough with flour and put it on a lightly floured surface (a smooth countertop is ideal). Cover with a large piece of plastic wrap or parchment and roll the dough out to a 12-inch diameter circle. Carefully peel off the plastic wrap, roll the dough onto the rolling pin and unroll over a 10-inch tart pan with removable base.
Press the dough into the pan and up the sides, trimming the top edges of the dough flush with the pan by running the rolling pin over the top (save the scraps, see note).Put the pan into the refrigerator to chill while you make the filling.
Make the filling
Preheat oven to 325 degrees.
Beat the mascarpone, yogurt, eggs, vanilla, sugar, flour and salt in an electric mixer with the paddle attachment or in a food processor until very smooth. Scrape into the tart pan.
Place the pan on a baking sheet. Bake until the filling no longer jiggles in the center, 30 - 37 minutes. Cool completely on a wire rack, then remove the sides of the pan. Wrap in plastic wrap and chill in the refrigerator for at least 2 hours.
Just before serving, arrange the strawberries over the top of the tart or pile them up for a more rustic presentation.
Drizzle with honey or sprinkle with sugar to taste and garnish with fresh mint or basil leaves, if you like.
Save and re-roll the pastry scraps. They're great cut into simple cookies shapes, baked for 10-12 minutes at 350 degrees.
The tart will keep for a day or two, lightly covered with plastic wrap and stored in the refrigerator.