Combine plums, sugar, water, and cinnamon in a small saucepan. Simmer for 12 to 15 minutes until tender but still chunky. Set aside.
Mix Batter:
Whisk the egg yolks, milk, flour, 1 tablespoon sugar, vanilla, and salt until smooth.
Beat the egg whites with the remaining 2 tablespoons sugar to soft peaks, then fold them gently into the batter.
Cook and Tear:
Melt 2 tablespoons butter in an oven-safe skillet over medium heat. Add the batter and cook for 4 minutes. Broil for 2 to 3 minutes until the top is set and lightly browned.
Return the skillet to low heat. Tear the pancake into irregular bite-size pieces with two spatulas, add the remaining butter, and turn for 3 minutes until varied golden edges form. Dust with powdered sugar and serve with compote.
Notes
Fold the egg whites gently to preserve the pancake's light texture.
Tear rather than cut the pancake so the pieces remain irregular and tender.