Cut off a third of the bread dough. With lightly floured hands, flatten both portions into disks. Cover with plastic wrap and let stand while preparing filling, about 30 minutes.
Rinse chard and tear leaves form center ribs; discard center ribs and stems or save for another use.
Pour oil into a 12-inch frying pan or a 14-inch wok over medium-high heat; when hot, add garlic and stir until fragrant, about 1 minute, Add chard and stir frequently until evenly wilted, 12 to 15minutes. Transfer mixture to a strainer and let drain until cool enough to handle. Squeeze chard to remove all liquid, then corasely chop.
In a bowl, mix chard, 1 egg, ricotta, 1/4 cup cream, olives, lemon peel, nutmeg, salt, and pepper.
With a lightl floured rolling pin, on a lightly floured surface, roll the larger portion of dough into a 12-inch round about 1/4 inch thick. Brush off excess flour. Fit into a 10-inch cheesecake pan wit removable rime and fold excess dough down so that edges come about halfway up sides of pan; press dough gently against sides of pan. Add chard mixture and spread level. Roll remaining dough into a 10-inch round. Center over filling and pinch with the sides to seal. In a small bowl, beat remaining egg with remaining 2 tablespoons cream to blend. Brush top crust with egg mixture; discard remainder.
Bake in a 375º regular or convection oven until top is richly browned, 35 to 40 minutes. Let cool about 10 minutes, then run a small sharp knife between tart and pan rim to loosen; remove rim. Use a serrated knife to slice into wedges. Serve warm or cool.