Preheat oven to 375 degrees F (220 degrees C).
Heat a nonstick pan on medium heat. Once hot, add the oil. Saute the onion and garlic until golden brown. Add in the artichoke and spinach. Saute until the spinach wilts then remove from the heat and place in a bowl. Mix in the chicken until well combined. Season with salt and pepper.
Evenly place the mixture across the center of the puff pastry sheet and roll up tightly. (It should be about the circumference of a cucumber or a little bigger)
Place it seam side down on a parchment paper lined baking sheet. Brush the top and sides with oil.
Bake for about 25 - 35 minutes until the internal temperature reaches 160 degrees using a thermometer and the puff pastry is golden brown. Once done, remove from the oven and set aside for 3 - 5 minutes before slicing into portions.
For the veloute: In a saute pan over medium heat melt the butter and stir in the flour, cook until light golden brown. Whisk in the broth. Add the thyme and turn down the heat to low simmer to build flavor. Season with salt and pepper to taste. Once flavorful whisk in the cream. Continue to simmer to a smooth creamy consistency.
Serve with sauce and bread. Garnish with thyme.