Step 1Drain the canned mandarin oranges, reserving the juice; you should have 1 1/2 cups reserved juice (if you are short, make up the difference with additional orange juice).
Step 2In a large, heavy-bottom saucepan, combine the canned oranges, reserved mandarin juice, 2 1/2 cups orange juice, ginger and sugar over high heat.
Step 3Bring the mixture to a strong simmer and cook, stirring frequently, until the compote is reduced to sauce consistency, about 40 minutes. As the compote reduces, the color will deepen to a rich apricot shade.
Step 4When the compote is almost reduced, in a small bowl combine the remaining one-fourth cup orange juice with the cornstarch, whisking to thoroughly combine and form a slurry.
Step 5Add the slurry into the reduced compote, stirring until the compote thickens, about 1 minute. Remove from heat. This makes about 1 1/2 cups compote. You might not use all of the compote for the remainder of the recipe; to store, cool the compote then cover and refrigerate until needed. The compote will keep for about a week, refrigerated. Gently warm in a saucepan before serving.
Step 1Cut the bread: Use a 2 1/2-inch round cookie cutter to cut through the center of each slice to form a round. Spread 1 tablespoon mascarpone over each of half of the rounds, then cover with a remaining round of bread. Repeat, forming 18 sandwiches.
Step 2In a large bowl, whisk together the eggs, milk, cinnamon and sugar to form a batter.
Step 3Heat a large flat skillet over medium heat. Add 1 to 2 tablespoons canola oil to the pan (enough to form a thin film), heating until the oil is hot.
Step 4Dunk a sandwich quickly into the batter, coating on all sides. Place the sandwich in the skillet and fry until golden and crisp on both sides, about 1 minute per side.
Step 5Repeat with the remaining sandwiches until all are fried, holding the fried sandwiches in a warm place.
Step 6To serve, place 3 warm sandwiches on each plate, topping with a spoonful of compote. Serve immediately.