This easy tart, inspired by turtle candies, combines caramel, pecans, and chocolate for a rich filling. Unwrapping the caramels takes a few minutes, but the rest of the tart can be assembled in very little time, and the crust can be made ahead of time and frozen for up to 2 weeks. The tart can be chilled in the refrigerator for up to 3 days before serving.
Preheat oven to 350 degrees F.
Combine shortbread dough with oats and ground pecans. Gather dough into a ball and press evenly into a 9-½-inch tart pan with removable bottom. The crust should be about ⅛ inch thick on the bottom and slightly thicker on the sides. Bake crust 12 minutes, until golden brown. Remove from oven and cool.
Warm ganache over low heat or in microwave, until loose and liquid. Spread ¾ cup ganache over bottom of tart. Refrigerate 15 minutes. Meanwhile, melt caramel with cream over medium-low heat, paying careful attention so that it does not burn. Stir in the pecans. Remove chilled tart from refrigerator and pour caramel mixture over the entire chocolate layer. The caramel should spread slowly and evenly over the ganache. If necessary, even out the caramel very gently with a spatula. Return tart to refrigerator for 10 minutes.
Pour remaining ¼ cup ganache into a pastry bag (or a sandwich bag with a small cut at one corner). Squeeze out ganache in parallel stripes over the caramel layer. Run knife through chocolate in perpendicular or diagonal lines to create decorative pattern. Serve at room temperature.
Blend butter and brown sugar. Add flour and mix briefly, until dough can hold ball shape. Set aside and chill.
Pour chocolate chips into mixing bowl. In a heavy saucepan, heat cream over medium-high heat until it just begins to simmer. Remove from heat immediately and pour hot cream over chocolate chips. Stir steadily until all chocolate is melted and blended.