Preheat the oven to 325 degrees F and grease a half sheet pan (13 x 18 inches), with edges, with floured baking spray.
In a large bowl, melt the butter in the microwave.
Add half of the white chocolate chips to the melted butter. Set aside and do not stir the mixture.
In a mixer, beat the eggs on medium speed until foamy.
Gradually add the sugar, beating on medium speed until the mixture is creamy. Stir in the white chocolate chip mixture.
Add the flour, salt, and almond flavoring, mixing at low speed until just blended.
Spread ¾ of the batter into the prepared pan. Set the remaining batter aside.
Bake for 10 to 12 minutes or until lightly brown.
Stir the remaining white chocolate chips into the remaining batter and set aside.
Warm the raspberry jam and spread evenly over the warm baked crust.
Gently drop tablespoons of the remaining batter over the fruit spread. Swirl with a metal spreader to even out until a little raspberry jam is peeking through all over. Sprinkle with the sliced almonds.
Place back in the oven for an additional 20 minutes or until a toothpick comes out clean.
Cool completely and cut into 2-inch squares, further cutting into 1-inch squares.