TRUFFLES: Combine the chocolate, cream, and butter in a small heatproof bowl, set over simmering water, and let melt.
When almost melted, remove from the heat and stir the mixture until smooth. Stir in flavoring of your choice and refrigerate until thick enough to mound on a spoon, stirring occasionally, about 30 minutes.
Line a baking tray with waxed or parchment paper. Scrape the chocolate mixture into pastry bag fitted with a #3 plain tip. Pipe eight 1-inch mounds onto the prepared tray.
Place 1 raspberry in center of each chocolate mound and pipe a little more of the chocolate mixture to enclose completely. Refrigerate until firm, about 15 minutes.
CAKE: Position a rack in the center of oven and preheat oven to 350 degrees. Spray 8 oversize muffin cups with cooking spray. Line bottoms with rounds of waxed paper. Set aside.
In the top of a double boiler or a small heatproof bowl set over simmering water, melt together the chocolate and butter. Cool slightly.
Meanwhile, in the large bowl beat on high speed, eggs, egg yolks, and sugar until tripled in volume, about 5 minutes.
On low speed, add in the chocolate mixture just until combined. Remove the bowl and fold in the flour, using a rubber spatula.
Spoon a little of the batter into each of the prepared cups top with 1 truffle, and cover with the remaining batter.
Arrange cups on a baking tray and bake 15 minutes or until edges of the cakes begin to pull away from the sides of the cups. Let stand 10 minutes.
Invert onto individual dessert plates and carefully peel off paper. Serve warm with whipped cream or ice cream next to each cake and a few fresh raspberries.