Start by dicing some onion, mushroom, apple, and mincing some garlic. Heat a nonstick pan over medium heat. Add in vegetable oil and then the diced onions. Season with salt and let these cook until golden brown and caramelized. This will take about 20 minutes.
Once the onions are nice and golden, remove from the pan and place in a bowl. Set aside. In the same pan, add in butter. Let the butter melt and then add in mushrooms. Saute for about 5 minutes, or until the mushrooms are tender, or have reached your desired texture. Mushrooms release a lot of moisture, so let this evaporate. Then add in minced garlic and dried thyme and saute for another minute. Add in white wine, scraping up any mushrooms bits that have stuck to the bottom of the pan. Cook until all the liquid has evaporated. Taste and season with a pinch salt, if necessary!
Remove these from the pan and place with the onions.
Again, in the same pan, heat another tablespoon of butter. Let this melt, and add apples and a touch of sugar. Stir to combine. Cook the chopped apple for about 8 - 10 minutes, or until the apples start to caramelize and are soft.
Once soft, place in the same bowl as the mushrooms and onion. Into the mixture, stir in shredded gruyere and goat cheese. Taste and re-season with salt if needed!
Now, preheat the oven to 350 degrees F and line a baking sheet with a silicone mat. Remove the store bought mini pastry tart shells and fill with the onion, mushroom, apple, and cheese mixture. Bake these for 5 - 10 minutes, or until the mixture is hot!
Top with minced fresh chives and serve immediately!