Remove the heavy stems from the chard and discard.
Wash the leaves, pat dry, and chop coarsely.
Heat the olive oil in a skillet, add the onion, and saute over medium heat for 3 minutes.
Add the garlic and chard and saute for 4 to 5 minutes more, stirring often.
Add the cheese and toss in the skillet for 1 minute, then add the seasonings.
Turn the mixture into a food processor and puree.
Transfer to a bowl and let cool.
The spread can be chilled if made ahead of time, and allowed to return to room temperature.
Spread on crackers and decorate with cherry tomato halves.