Assembly
Step 1
Caramelized onions: In a frying pan over medium-low heat, drizzle olive oil and add onions. Cook until softened and fragrant. Add apple cider and Meyer Lemon Honey Vinegar. Simmer on medium to medium-low heat until liquid has evaporated and onions have caramelized. Set aside to cool.
Step 2
Pre-heat oven to 375ºF.
Step 3
Place a 9-inch tart pan (removable bottom preferred) onto a large sheet pan with rimmed edges. Brush lightly with butter.
Step 4
Remove phyllo pastry from package and separate 1 sheet. Brush one side with butter and use it to line the tart pan, tucking in edges or folding as needed. Be sure to keep remaining phyllo pastry covered or wrapped to prevent drying.
Step 5
Brush another sheet with butter, fold at 1-inch intervals (can be rough), alternating in direction (like folding a fan), then wind the strip up along itself to create a flower. Place that in the middle of the lined pan. Repeat the brushing and folding steps, but wrap each strip around the middle flower until the tart pan has been filled.
Step 6
Stuff the gaps evenly with caramelized onion and single layers of apple slices. Brush the top with butter. Bake for 35-40 minutes. Remove and reduce heat to 350ºF.
Step 7
Meanwhile, prepare custard by mixing milk, egg yolks, cheddar cheese, Hot Deli Mustard, garlic, sage, thyme, salt, and pepper. Pour evenly into tart pan. Place back in oven for 30-40 minutes, or until browned on top.
Step 8
Remove from oven and let cool 15 minutes before serving.
