Preheat oven to 375°F. Fry bacon in a large skillet over medium heat until crisp, 7 to 9 minutes. Transfer to a paper-towel-lined plate, cool and finely chop. Discard all but 2 teaspoons grease from skillet; return to medium heat, add mushroom stems, onion, jalapeño and salt. Cook, stirring occasionally, until very dry and lightly browned, about 8 minutes. Transfer to a food processor and pulse just until chopped. Add bacon and parsley; pulse until combined. Spoon some of the mixture into each mushroom cap, top with 1/4 teaspoon sour cherry spread and arrange on a large baking sheet. Bake until mushrooms are tender and lightly browned, 20 to 25 minutes. Let cool slightly. Serve warm or at room temperature.