Hands-on 36 minutes
Total 50 minutes
Center a rack in the oven and preheat to 450°F.
In a heavy skillet, melt the butter over medium-high. Sauté the onion, stirring occasionally, until golden, about 15 minutes.
Add the water and deglaze the skillet, loosening any brown bits and cooking until the water evaporates. Stir in the thyme and cook until
the onion is a deeper brown, about 10 minutes.
While the onion is cooking, cut off 1⁄3 of the pastry sheet, cutting lengthwise along the perforated line. Halve the piece again lengthwise to create 2 (10- x 3-inch) strips. Cut each strip into 8 triangles.
Place the triangles on a parchment paper-lined baking sheet, prick the pastry all over with a fork; bake until golden, about 10 minutes.
Spread the goat cheese onto the triangles; top with the onions.
Garnish with the fresh thyme leaves and serve immediately.