Melt butter and chocolate in a bowl over simmering water or in microwave on medium (50 percent) power. Stir in cookie crumbs. Press onto bottom and sides of 24 mini muffin cups. Let stand at room temperature or refrigerate until set. Place one raspberry or blackberry in the center of each muffin cup.

Melt chocolate in a small bowl over simmering water. Turn off heat and leave bowl over water to keep chocolate warm. Beat 1/2 cup butter in a small bowl until fluffy. Beat in 1/4 cup sugar and cocoa powder. Whisk yolks, water, remaining 1/4 cup butter and 1/4 cup sugar in a medium metal bowl. Place over a saucepan of simmering water (do not let bowl touch water). Whisk constantly until a candy thermometer reads 160Fº, about 6 minutes. Remove bowl from top of the simmering water.

Beat warm yolk mixture with an electric mixer until thickened and cool, about 5 minutes. Beat in butter-cocoa mixture; fold in warm melted chocolate and vanilla. Beat heavy cream until soft peaks form in separate bowl; fold whipped cream into chocolate yolk mixture. Fill pastry bag with truffle batter and pipe into prepared crusts, covering berry. Refrigerate until firm, at least 4 hours or overnight. (Can be made 4 days ahead and refrigerated.)

If you don't have a pastry bag, just spoon the filling into plastic bag and snip off the tip of the bag. Any mini muffin pans will work, but the silicone pans will make removal of the truffles even easier.

Combine berries, sugar, lemon juice, cornstarch and water in a medium saucepan. Bring to a simmer over medium heat and stir until berries release juices and thicken, about 5 minutes. Cool slightly. Serve warm, or cover and refrigerate up to 4 days. Reheat before serving.

Run a knife around truffles to release from pan. Serve with warm berry compote.