Cook the tart shells according to the package instructions.
Heat a medium skillet over medium-high heat. Add in the butter, wait for it to melt and foam, then add in the shallots and cook for two to three minutes or until they soften.
Add the pears to the pan and cook for three more minutes or until the pears start to soften as well.
Add the sugar, vinegar, and hot water. Cook for two minutes, then add in the thyme and a pinch of salt.
Cook until all the moisture has evaporated.
Remove the pan from the heat, spoon the pears into the pre-baked tart shells, and top with the crumbled blue cheese.