Take your chard stems with leaves in the hand and break them apart where the leave and the stem meet. That way its easier to rinse off impurities. Pat dry after rinsing.
Cut your stems into smaller pieces and keep in a bowl aside.
Cut your leaves small as well and keep separate from the cut stalks. The leaves need short cooking then the stems.
Cut your bacon into small pieces.
Heat up a pan with the olive oil and butter and add in your onion slices. Cook your onion soft.
Add the bacon pieces and fry your bacon until crisp over medium to high heat.
Throw in your swiss chard stem pieces and stir cook for a minute on high heat. Then sautee your swiss chard stalk pieces over medium heat.
Season with salt, black pepper and thyme, and mix.
Sautee your chard stems until they look almost cooked through.
Now add half of the swiss chard leaves to your pan and over high heat mix and cook so that the leaves reduce in size. Then add the remaining rainbow chard leaves and cook further over high heat until the leaves have considerably reduced in size.
Reduce heat to medium and pour cream over the chard in the pan. Cook and mix for another 1-2 minutes.
Serve your sauteed swiss chard with bacon hot.
You can use dried thyme or rosemary or savory or a mix of all these spices. Sometimes I like to use a Italian seasoning blend too.