Preheat the oven to 350F. Line a standard muffin pan with 12 parchment muffin cups.
In a medium microwavable bowl, add the butter and microwave in 15 second intervals until melted. Add the almond flour, maple syrup, cinnamon, and salt and mix to combine until a sticky crumbly dough forms. It’s best to use your hands at the end to make sure everything is well mixed.
Divide the mixture between the muffin cups (about 2 tablespoons per cup), then use your fingers to press it down and up the sides of the muffin cup. It’s important to press the dough enough so that it goes all the way up the sides for the whipped yogurt to go into. Start by pressing the bottom and then work up the sides (watch the video!). If it’s sticking to your fingers too much, dip them in water and keep molding!
Bake for 10 minutes, or until the edges turn light golden. The bottoms may puff up and crack a bit - that’s fine! If the cracks are big, you can press gently to try and make the dough stick together but once it firms up it will be fine. Let cool completely before adding the whipped yogurt.
In a large bowl, add the whipping cream and use an electric beater to beat on high until stiff peaks form (about 2-4 minutes). Add in the yogurt, sugar, and vanilla (if using) and beat until combined and fluffy (just about 30 seconds). Taste and add more sweetener, if needed.
Add a scoop of whipped yogurt into each (completely cooled) tart cup so that it fills almost to the brim. Top with berries (or whatever toppings you want) and dig in! I also like to sprinkle a bit of salt on top at the end.