Step 1: Preheat your oven to 350°F (175°C). Grease your 9x13 inch baking pan with cooking spray or line it with parchment paper for easy removal later.
Step 2: In a large mixing bowl, combine the softened butter and sugar. Using a spatula or hand mixer, cream them together until the mixture is light and fluffy.
Step 3: Open the can of Solo Almond Paste and add it to the butter and sugar mixture. Mix until thoroughly combined, ensuring there are no lumps of almond paste left.
Step 4: Gradually add the all-purpose flour to the mixture, stirring until just combined. Be careful not to overmix, as this can lead to dense bars.
Step 5: Gently fold in the white chocolate chips and sliced almonds, making sure they are evenly distributed throughout the batter.
Step 6: Pour the sweetened condensed milk over the batter and mix until combined. This will create a luscious and gooey layer within the bars.
Step 7: Pour the batter into the prepared baking pan, using a spatula to spread it evenly. Make sure to smooth the top for even baking.
Step 8: Place the pan in the preheated oven and bake for 25-30 minutes, or until the edges are golden brown and the center is set. The bars should be slightly soft in the middle but will firm up as they cool.
Step 9: Once baked, remove the pan from the oven and allow it to cool completely in the pan. Once cooled, lift the bars out using the parchment paper (if used) and cut them into squares or rectangles.