Line an 8x8 inch baking pan with foil or parchment paper and grease. Preheat oven to 375 degrees.
In a small bowl, whisk together the sugar, flour, baking soda, baking powder, and salt for the crust. Add melted butter and mix. Reserve 3/4 cup of the mixture, set aside. Press remaining mixture into the bottom of your prepared baking pan.
In a medium bowl, use a spoon to stir together raspberries, flour, and sugar - stir until just combined and flour is incorporated, being careful not to overmix or smash berries too much. Pour mixture over crust.
Sprinkle reserved crumb mixture over raspberry filling. Sprinkle chopped pecans if desrired. Bake for 25-30 minutes until crumb topping is golden. Allow to cool before cutting into squares.
In a microwave safe bowl combine chocolate chips and heavy cream. Microwave on medium power for 2 minutes. Stir until smooth. Drizzle over bars and serve.
*Note: Serving suggestions include serving warm with vanilla ice cream, or cold after being chilled for at least 1 hour.