In a bowl combine mascarpone cheese and honey together. Set aside.
Toast walnuts in a pan over medium-low heat until fragrant. Chop and set aside.
To assemble one sandwich, spread half of the cheese mixture on one slice, and then spread half of the nutella on the other slice. Place sliced strawberries and walnuts on the slice with cheese. Close the sandwich with the nutella slice. Repeat the process for the second sandwich.
Heat a pan on medium and melt butter. Cook sandwiches on each side until golden brown.