Take phyllo dough out of the freezer and let thaw at room temperature.

Blanch asparagus by boiling in water rapidly for three to four minutes. Using tongs, dunk into ice-cold water for five minutes. Drain well.

In heavy-bottom saucepan over medium heat, sauté shallots in 4 tbsp. butter for three to five minutes.

Add Add thyme and mushrooms to shallots and continue cooking for another five to ten minutes.

Place parchment paper on rimmed baking sheet.

Sautee garlic in saucepan with one 8 tbsp. butter until butter is melted and garlic is fragrant. Allow to cool slightly

Working as quickly but carefully as possible, take two or three sheets of the phyllo dough by the corners on one side and gently lower to the parchment-lined baking sheet.

Using a pastry brush, brush garlic butter across the phyllo dough, leaving an outer edge where you want your tart to be crispier, if desired.

Take another two or three sheets of phyllo dough from the original set, layer it over the buttered sheets on the parchment, and using the pastry brush, sweep more garlic butter across the phyllo dough.

Repeat this until all of the phyllo dough has been used up. This will seem like a lot of butter, and incredibly greasy, but the phyllo dough will soak up the butter and be flaky and textured.

Sprinkle half of the parmesan cheese onto the prepared phyllo dough.

Arrange the blanched asparagus and sautéed mushrooms onto the tart.

Sprinkle with remaining parmesan cheese.

Bake in 375 degree oven for 15-20 minutes, or until cheese is melted and edges of phyllo turn a deep golden brown.

Allow to cool for five minutes.

Slice and serve immediately.