Line a large sheet pan with parchment paper, ensuring a bit of overhang for easy removal of the treats. Set aside.
In a large saucepan, melt the butter over medium-low heat.
Add the miniature marshmallows to the saucepan and heat, stirring frequently, until fully melted and smooth. Remove from heat and stir in the Rice Krispies cereal until well combined.
Gently press the Rice Krispie mixture into the prepared pan, spreading it evenly. Allow it to set for about 30 minutes.
Once the Rice Krispie treats have cooled and set, carefully remove them from the pan. Use a small heart-shaped cookie cutter to cut out mini heart shapes. Set aside.
In a microwave-safe bowl, melt the vanilla almond bark in 15-second increments, stirring between each interval, until fully melted and smooth. Stir in the strawberry extract and red food coloring.
Transfer the melted almond bark into a pastry decorating bag or a zip-top bag with a small corner snipped off. Drizzle the melted almond bark over the mini heart Rice Krispie treats. Immediately sprinkle with Valentine's Day themed sprinkles.
Serve the Mini Heart Valentine's Rice Krispie Treats immediately or store them in an airtight container at room temperature.