Preheat oven to 350 degrees.
Set aside a tart mold with a removable bottom, preferably 9" wide bottom x 2" high sides.
Cream together the butter, egg, sugar, and extract.
Stir in flour and baking powder. Dough will be soft and crumbly.
Press evenly into bottom and up sides of pan.
Bake in preheated oven for 15 minutes. Remove from oven and let cool on wire rack.
Mix together the cream cheese and sugar until smooth.
Spread evenly into cooled crust.
In a small saucepan, whisk together sugar, cornstarch, and orange juice.
Add sprigs of thyme and stir over medium heat on stove top until mixture starts to boil.
Continue stirring for one minute at full boil.
Remove from heat. Discard thyme sprigs and set aside to cool.
Meanwhile, peel and slice peaches evenly.
Place slices on top of cheese mixture, overlapping beginning on outer edge.
Continue working into the middle until all of the filling is covered with the sliced peaches.
Slowly pour the glaze evenly over the peaches to cover.
Chill in refrigerator at least 4 hours or overnight.
Carefully remove from tart pan, cut , and serve.