First make the ganache. Place chocolate chips and heavy cream in small bowl and microwave for 1-2 minutes in 30 second intervals until melted, stirring between each interval. Stir in vanilla extract and cover and place in fridge.
Place the chopped white chocolate and butter in medium bowl and microwave for 1-2 minutes in 30 second intervals until melted, stirring between each interval. Set aside.
In large bowl whisk together the egg, egg yolk, light brown sugar and pumpkin puree until combined. Pour in the white chocolate mixture and whisk until combined.
Add flour, pumpkin pie spice and salt to wet ingredients and whisk until there are no lumps left.
Generously butter and flour two (8 oz) ramekins. Fill both ramekins with lava cake batter. Spoon 1-2 heaping teaspoons of ganache right into center. Use a spoon to scoop pumpkin lava cake mixture over the ganache. Cover and place in fridge for 15 minutes.
Preheat oven to 400°F. Bake lava cakes for about 18 minutes or until firm on the edges and jiggly in the center. Let cool for 3 minutes and then loosen the edges of the cake with a butter knife. Turn onto small plates and serve with some vanilla ice cream.
Make sure you let the ganache sit in the fridge for at least 30 minutes so it hardens. You want it to be hard so you can drop a dollop of it in the middle of the cake batter. Don't worry as it will melt when baked.
Microwave the white chocolate and butter in 30 second intervals until just melted. If you microwave too long, the chocolate will separate.
Do not skip buttering and flouring the ramekins, otherwise you will not be able to get the cake out.
You know the lava cake is done when the edges are firm, but the center is still slightly jiggly.
Let the lava cake cool for 3-5 minutes before flipping over on plate. You can also just eat out of ramekin as well.