Set out the tart cherries in a strainer in the sink until completely thawed. Shake off all excess liquid and place in a large bowl.
Add in the sugar, (this is to taste depending on preference and tartness of the cherries you are using; I generally always do the full 1 and 1/2 cups to balance the tart) cornstarch, salt, lemon juice, vanilla, and almond extract. Toss gently to combine and set aside while making the crisp.
Preheat the oven to 350 degrees F.
Lightly grease an 8 inch cast-iron skillet.
In another large bowl, toss together the flour, oats, brown sugar, salt, cinnamon, nutmeg, and chopped pecans.
Cut the butter into small cubes and then cut that butter into the mixture. Use your fingers to work the butter into the mixture until a thick "dough" has formed.
Using a slotted spoon, spoon the cherry filling into the bottom of the skillet and throw away the leftover juices in the bottom of the bowl. You don't want the filling too liquidy because it will become more liquid while being baked so get rid of most of the extra liquid.
Top the cherry filling evenly with the crumble. You'll only need about 90% of the crumble and the rest you can eat or discard :)
Place the skillet on a baking sheet (in case anything spills over) and in then in the oven.
Bake for 35-40 minutes or until lightly golden brown on top.
Remove and allow to slightly cool.
While it's baking, make the glaze: add the powdered sugar to a bowl and slowly beat, with hand mixers, in the heavy cream. Add the cream just until a thick glaze forms.
Transfer the glaze into a small plastic bag and cut off the tip. Pipe the glaze over the crisp.
Serve the crisp topped with plenty of vanilla bean ice cream!