Lay a chard leaf flat on a cutting board or working surface. The smooth side of the leaf should be facing down.
Cut and remove the toughest part of the stem at the base of the leaf. Then bring the two ends of the leaf together, covering the gap you just created.
Add a spoonful of the filling to the bottom of the leaf right at the center.
Roll. Overlap the bottom end over the filling and fold both sides on top (envelope-like), then roll upwards until you reach the top end of the leaf. Roll tightly but without squeezing it too much. Repeat the process for the remaining leaves. If a leaf is too large, you may cut it in half to create two rolls.
Prepare the cooking pot. Lay the smaller, uncooked chard leaves at the bottom of a medium-sized cooking pot (not a narrow pot).
Place the chard rolls in the pot tightly close together so they won't unroll while they cook.
Pour in the crushed tomatoes (or fresh, grated tomatoes) and the olive oil.
Place a plate on top of the rolls to hold them down while they cook.
Pour in 2 cups of hot water (or vegetable stock).
Simmer over medium-low heat, partly covered, for about 40 minutes. The plate pressing down the chard rolls will make the sauce look like more than it is. So keep that in mind. We want the rolls to absorb the water, leaving mostly oil in the pot. To check on this, you can take the pot off the heat for a minute and remove the plate carefully to see how much sauce is actually left in the pot.
Let the rolls sit in the cooking pot for 10-15 minutes off the heat.
Serve with fresh lemon squeezed on top and an extra drizzle of extra virgin olive oil if you like!